A pre-filter with back-flushing function

Abstract

The application discloses a pre-filter with backwashing function, which comprises a shell part, a filter core, the shell part is provided with a water inlet, a water outlet and a blowdown port, the filter core cooperates with the shell part to form a raw water cavity and a clean water cavity, a water inlet channel is arranged between the water inlet and the raw water cavity, a backwashing channel is arranged between the clean water cavity and the water inlet, and a plugging piece for opening and closing the blowdown port is arranged at the blowdown port; the filter core comprises a laminated filter screen, a movable support and a fixed support, the laminated filter screen comprises a plurality of laminations which are matched between the movable support and the fixed support; the shell part is provided with a switch assembly capable of controlling whether the water inlet channel is opened or not, and the switch assembly drives the movable support to move along the axial direction of the filter core when being opened and / or closed, so that the laminations are pressed tightly or loosened. The application adopts the switch assembly to provide driving force for controlling the tightness and looseness of the laminations, is not affected by the water pressure, and greatly improves the efficiency and effect of backwashing of the pre-filter.

Description

TECHNICAL FIELD

[0001] The present application relates to the filter technical field, particularly to a front filter with backwashing function. BACKGROUND

[0002] The municipal tap water has secondary pollution such as pipeline corrosion and silt, which causes the poor water quality of household water. A front filter is usually installed on the household pipeline to improve the water quality. The filter core of the front filter on the market adopts a laminated filter screen for filtration. The laminated filter screen is composed of a group of laminates (also called discs) with grooves on both sides. The intersection points of the grooves and edges of the laminates can intercept the solid matters in the water. The laminated filter screen has the functions of surface interception and depth coagulation, thus greatly improving the filtration effect.

[0003] The filter core of the front filter needs to be backwashed after a period of use to clean the filter core and improve the service life of the filter core. For the front filter with laminated filter screen, the laminates are usually cleaned by backwashing. When backwashing, the water pressure difference ΔP and spring on both sides of the filter core are used to change the water path to achieve the loose and tight adjustment of the laminates. However, when the water pressure is insufficient, the pressure difference ΔP at the end face of the backwashing structure is insufficient to make the backwashing sub-element overcome the reaction force of the spring, so that the laminates cannot be switched to the loose state, which affects the efficiency and effect of backwashing. SUMMARY

[0004] The present application provides a front filter with backwashing function, which uses a switch assembly instead of water pressure difference to provide driving force for the loose and tight control of the laminates, thus greatly improving the efficiency and effect of backwashing.

[0005] The technical scheme adopted by the present application to solve the technical problem is as follows: a front filter with backwashing function, comprising a shell part and a filter core. The shell part is provided with a water inlet, a water outlet and a sewage outlet. The filter core is installed in the shell part and cooperates with the shell part to form a raw water cavity communicating with the sewage outlet and a clean water cavity communicating with the water outlet. An inlet channel is arranged between the water inlet and the raw water cavity. A backwashing channel is arranged between the clean water cavity and the water inlet. A blocking piece for opening and closing the sewage outlet is arranged at the sewage outlet.

[0006] The filter core comprises a laminated filter screen and movable supports and fixed supports distributed in the axial direction of the filter core. The laminated filter screen comprises a plurality of laminates cooperated between the movable supports and the fixed supports. The shell part is provided with a switch assembly capable of controlling the opening and closing of the inlet channel. The switch assembly drives the movable supports to move in the axial direction of the filter core when the switch assembly is opened and / or closed, so as to press or loosen the plurality of laminates.

[0007] Further, the switch assembly drives the movable support to move towards the fixed support when the switch assembly is turned on, and releases the movable support when the switch assembly is turned off, and the movable support moves away from the fixed support under the action of a restoring member cooperating with the fixed support and / or the housing part.

[0008] Further, the switch assembly comprises a movable valve plate rotatably arranged on the water inlet channel and a fixed valve plate fixed on the water inlet channel, the movable valve plate is provided with a first water passing hole, the fixed valve plate is provided with a second water passing hole, the movable valve plate cooperates with the fixed valve plate, and the movable valve plate is driven to rotate by a driving member so that the first water passing hole and the second water passing hole correspond or misalign with each other; the movable valve plate drives or releases the movable support through rotation.

[0009] Further, the movable valve plate is provided with a plurality of driving protrusions distributed along the circumference of the movable valve plate, the movable support is provided with a plurality of driven protrusions distributed along the circumference of the movable support, and the driving protrusions of the movable valve plate and the driven protrusions of the movable support correspond or misalign with each other through rotation.

[0010] Further, the driving member is a valve rod, the valve rod is rotatably connected to the housing part about the axis of the valve rod, and is fixed opposite to the movable valve plate, one end of the valve rod extends out of the housing part and is provided with a flushing knob, and the other end of the valve rod penetrates through the water purification cavity and is connected to the blocking member, so that the valve rod drives the blocking member to open or close the drain opening through rotation.

[0011] Further, the blocking member is sleeved on the other end of the valve rod and can rotate with the valve rod and axially move relative to the valve rod, and the blocking member is provided with external threads, and the external threads are threadedly connected with internal threads of a fixed sleeve fixed in the water purification cavity.

[0012] Further, the number of the first water passing holes and the second water passing holes is equal and each is a plurality, the plurality of first water passing holes are distributed along the circumference of the movable valve plate, and the plurality of second water passing holes are distributed along the circumference of the fixed valve plate; the fixed valve plate is provided with a plurality of spiral flow channels distributed along the same rotation direction, the spiral flow channels are inclined water channels or spiral water channels, one end of each spiral flow channel forms the second water passing hole, and the other end of each spiral flow channel forms a water outlet hole capable of laterally discharging water.

[0013] Further, the restoring member comprises an elastic member, and the elastic member abuts and cooperates between the movable support and the fixed support or the housing part.

[0014] Further, the filter element further comprises a main filter screen, the main filter screen is located inside the laminated filter screen to perform secondary filtration on water passing through the laminated filter screen; the filtration precision of the main filter screen is higher than that of the laminated filter screen, and the main filter screen is sleeved on a filter element support.

[0015] Further, the backwashing channel is provided with a backwashing filter screen, the filtering precision of the backwashing filter screen is higher than the filtering precision of the laminated filter screen, and the backwashing filter screen is sleeved outside a backwashing support.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] 1. Since the switch assembly capable of controlling whether the water inlet channel is opened or not is used to drive the movable support to move along the axial direction of the filter core when being opened and / or closed, so as to make the plurality of laminated plates press against each other or be loosened, the switch assembly is used to replace the water pressure difference to provide the driving force for controlling the loosening and tightening of the laminated plates, and the efficiency and effect of the backwashing of the pre-filter are greatly improved.

[0018] 2. The switch assembly preferably comprises the movable valve plate and the fixed valve plate, and has the characteristics of simple structure and convenient installation. In particular, the movable valve plate and the movable support are linked and matched through the driving convex part and the driven convex part, so that the movable valve plate and the movable support do not need to use an additional transmission part for transmission, thereby making the overall structure simple, reducing the cost of parts, simplifying the assembly process, and ensuring the stability of the cooperation between the movable valve plate and the movable support.

[0019] 3. The other end of the valve rod is connected with the plugging piece, so that the valve rod can drive the movable valve plate to rotate and drive the plugging piece to open / close the blow-off port through rotation, thereby making the operation convenient when the present application is backwashed, and only one operation action is needed to realize the backwashing function.

[0020] 4. The setting of the spiral flow water channel makes the water flow rotate into the raw water cavity when the switch assembly of the present application is opened, so that the filter core surface is continuously scoured through rotation, and the water flow is always in a turbulent state, so that the filter core surface is not easy to be contaminated.

[0021] 5. The filter core further comprises the main filter screen, so that the present application uses double-layer filter screens for progressive filtration, which not only can greatly improve the filtering effect, but also can effectively protect the main filter screen, thereby prolonging the service life of the filter.

[0022] 6. The backwashing channel is provided with a backwashing filter screen, so that the water flowing through the backwashing channel can be filtered before flowing to the water outlet in the filtering state.

[0023] The present application will be further described in detail in combination with the drawings and embodiments; however, the pre-filter with a backwashing function of the present application is not limited to the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1is the exploded schematic view of the present application (without the shell part);

[0025] Figure 2 is the exploded schematic view of the switch assembly of the present application;

[0026] Figure 3 is the front view (partly cutaway) of the present application;

[0027] Figure 4 is the cutaway view of the present application Figure 1 ;

[0028] Figure 5 is the cutaway view of the present application Figure 2 (not including the shell part);

[0029] Figure 6 is the structural schematic view of the present application in the filtering state (not including the shell part)

[0030] Figure 7 is the A-A cutaway view of Figure 6 ;

[0031] Figure 8 is the enlarged schematic view of the I part of Figure 6 ;

[0032] Figure 9 is the cutaway view of the present application in the filtering state;

[0033] Figure 10 is the structural schematic view of the present application in the backwashing state (not including the shell part);

[0034] Figure 11 is the B-B cutaway view of Figure 10 ;

[0035] Figure 12 is the enlarged schematic view of the II part of Figure 10 ;

[0036] Figure 13 is the cutaway view of the present application in the backwashing state;

[0037] In the figure, 1, shell part, 11, water inlet and outlet head, 111, water inlet, 112, water outlet, 12, filter shell, 121, sewage outlet, 122, raw water cavity, 2, filter core, 21, laminated filter screen, 211, laminated sheet, 22, movable support, 23, fixed support, 24, main filter screen, 25, filter core support, 26, clean water cavity, 3, movable valve sheet, 31, first water passing hole, 32, main movable convex part, 33, first clamping tooth, 4, fixed valve sheet, 41, second water passing hole, 42, water outlet hole, 5, spring, 6, backwashing filter screen, 7, plugging member, 8, valve rod, 9, fixed sleeve, 10, backwashing support, 20, backwashing knob. DETAILED DESCRIPTION

[0038] In the present application, the terms "first", "second" and the like are used only to distinguish similar objects, and are not used to describe a particular order or sequence, nor can they be understood to indicate or imply relative importance. In the description, the orientation or position relationship indicated by "up", "down", "left", "right", "inner", "outer" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application, and does not indicate or imply that the device must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the scope of protection of the present application. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] In addition, in the description of the present application, "a plurality of" means two or more, unless otherwise specified. The association relationship between the associated objects described by "and / or" indicates that there can be three relationships, for example, A and / or B can represent the three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the associated objects before and after it. In the description of the present application, unless otherwise specified and limited, the terms "mounting", "setting", "connecting" and the like should be broadly understood, for example, "connecting" can be fixedly connected, can be detachably connected, or integrally connected, can be mechanically connected, can be electrically connected, can be directly connected, can be indirectly connected through an intermediate medium, can be internal communication of two elements, and for those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] Please refer to Figures 1-13As shown, the pre-filter with backwash function comprises a shell part 1 and a filter core 2. The shell part 1 is provided with a water inlet 111, a water outlet 112 and a blowdown port 121. The filter core 2 is arranged in the shell part 1 and cooperates with the shell part 1 to form a raw water cavity 122 and a clean water cavity 26. Specifically, the raw water cavity 122 is formed between the outer side of the filter core 2 and the shell part 1, and the clean water cavity 26 is located in the inner side of the filter core 2. A water inlet channel is arranged between the water inlet 111 and the raw water cavity 122. A backwash channel is arranged between the clean water cavity 26 and the water inlet 111. The blowdown port 121 is provided with a blocking member 7 for opening and closing the blowdown port 121. The filter core 2 comprises a laminated filter screen 21 and movable supports 22 and fixed supports 23 distributed along the axial direction of the filter core 2. The laminated filter screen 21 comprises a plurality of laminates 211 stacked and cooperated between the movable supports 22 and the fixed supports 23. The shell part 1 is provided with a switch assembly capable of controlling whether the water inlet 111 of the shell part 1 is communicated with the raw water cavity 122. When the switch assembly is opened and / or closed, the movable supports 22 are driven to move along the axial direction of the filter core 2, so that the plurality of laminates 211 are pressed or released. Specifically, the shell part 1 comprises a water inlet and outlet head 11 and a filter shell 12. The water inlet and outlet head 11 is made of copper, but is not limited thereto. The water inlet and outlet head 11 is provided with the water inlet 111 and the water outlet 112. The water inlet 111 and the water outlet 112 are distributed on the left and right sides of the water inlet and outlet head 11. The water inlet and outlet head 11 is sealingly connected to the upper end of the filter shell 12. The blowdown port 121 is arranged at the lower end of the filter shell 12. The filter core 2 is arranged in the filter shell 12.

[0041] In the embodiment, when the switch assembly is opened, the movable supports 22 are driven to move towards the fixed supports 23. When the switch assembly is closed, the movable supports 22 are released. The movable supports 22 are driven to move away from the fixed supports 23 by the action of a restoring member cooperated with the fixed supports 23 and / or the shell part 1. In other embodiments, the movable supports 22 are driven to move when the switch assembly is opened and closed, so that the plurality of laminates 211 are pressed or released.

[0042] As a preferred mode, the switch assembly comprises a movable valve plate 3 rotatably arranged on the water inlet channel and a fixed valve plate 4 fixedly arranged on the water inlet channel. The movable valve plate 3 is provided with a first water passing hole 31, and the fixed valve plate 4 is provided with a second water passing hole 41. The movable valve plate 3 cooperates with the fixed valve plate 4. The movable valve plate 3 is driven to rotate by a driving member, so that the first water passing hole 31 of the movable valve plate 3 corresponds to or is staggered with the second water passing hole 41 of the fixed valve plate 4. When the first water passing hole 31 of the movable valve plate 3 corresponds to the second water passing hole 41 of the fixed valve plate 4, the switch assembly is opened, the water inlet channel is opened, and the water inlet 111 is communicated with the raw water cavity 122. When the first water passing hole 31 of the movable valve plate 3 is completely staggered with the second water passing hole 41 of the fixed valve plate 4, the switch assembly is closed, the water inlet channel is closed, and the water inlet 111 is disconnected from the raw water cavity 122. The movable valve plate 3 cooperates with the movable support 22 to have a transmission structure, so that the movable valve plate 3 drives or releases the movable support 22 by rotating. In other embodiments, the switch assembly comprises a moving member and a fixed member. The moving member is contacted or separated from the fixed member by axial movement to realize waterway switching. The moving member drives the movable support to move by axial movement.

[0043] As a preferred mode, the movable valve plate 3 is provided with a plurality of driving protrusions 32 distributed along the circumference of the movable valve plate 3. The movable support 22 is provided with a plurality of driven protrusions 221 distributed along the circumference of the movable support 22. The movable valve plate 3 drives the driving protrusions 32 to correspond to or be staggered with the driven protrusions 221 by rotating. Therefore, the driving protrusions 32 and the driven protrusions 221 constitute the transmission structure, but the structure of the transmission structure is not limited to this. In this embodiment, the plurality of driving protrusions 32 of the movable valve plate 3 are arranged at the inner end of the bottom end of the movable valve plate 3, and cooperate with the plurality of driven protrusions 221 on the movable support 22 through the middle through hole of the fixed valve plate 4.

[0044] The number of the first water passing holes 31 and the second water passing holes 41 is equal and multiple. The plurality of first water passing holes 31 are distributed along the circumference of the movable valve plate 3, and the plurality of second water passing holes 41 are distributed along the circumference of the fixed valve plate 4. The fixed valve plate 4 is provided with a plurality of spiral flow channels distributed along the same rotation direction. The upper end of each spiral flow channel forms the second water passing hole 41, and the lower end of each spiral flow channel forms a water outlet hole 42 capable of laterally discharging water. When the switch assembly is opened, each water outlet hole 42 laterally discharges water and forms a rotating water flow into the raw water cavity 122, so that the filter element 2 surface is continuously scoured by the rotating water flow, and the water flow is always in a turbulent water flow state, so that the filter element 2 surface is not easy to be contaminated.

[0045] In the embodiment, the driving member is a valve rod 8 which is rotatably connected to the housing part 1 and fixedly connected to the movable valve plate 3. Specifically, the movable valve plate 3 is provided with a first clamping tooth 33, and the valve rod 8 is provided with a plurality of second clamping teeth 81, and the first clamping tooth 33 is engaged with the second clamping tooth 81. One end of the valve rod 8 extends out of the housing part 1, and the other end of the valve rod 8 penetrates the clean water cavity 26 and is connected to the blocking member 7, so that the valve rod 8 drives the blocking member 7 to open or close the blow-off port 121 by rotating. Specifically, one end of the valve rod 8 penetrates the inlet and outlet head 11 upwardly and is provided with the flushing knob 20. In other embodiments, the blocking member is pluggably connected to the blow-off port, so as to control the opening or closing of the blow-off port by plugging or unplugging. In other embodiments, the driving member is an electric type which comprises a motor and a transmission assembly, and the motor is drivingly connected to the movable valve plate through the transmission assembly, and the transmission assembly can be a gear transmission assembly.

[0046] In the embodiment, the blocking member 7 is rotatably and axially movably sleeved on the other end of the valve rod 8, and the blocking member 7 is provided with an external thread which is threadedly connected to an internal thread of a fixed sleeve 9 fixed in the clean water cavity 26. In other embodiments, the blocking member 7 is fixedly connected to the valve rod 8, so that the valve rod 8 drives the blocking member 7 to rotate to open or close the blow-off port 121. At this time, the blocking member 7 can adopt a similar mechanism as the movable valve plate 3, that is, the blocking member 7 is provided with a drain outlet eccentrically, and the opening or closing of the blow-off port 121 is realized by corresponding or staggering with the blow-off port 121.

[0047] In the embodiment, the reset member comprises an elastic member, which is specifically a spring 5 which is abuttingly connected between the movable support 22 and the fixed support 23. In other embodiments, the elastic member is abuttingly connected between the movable support 22 and the housing part 1. In other embodiments, the reset member comprises a magnetic assembly, and the movable support is driven to reset by the magnetic force of the magnetic assembly.

[0048] The filter element 2 further comprises a main filter screen 24 which is made of stainless steel but is not limited thereto, and is located at the inner side of the laminated filter screen 21 to perform secondary filtration on the water passing through the laminated filter screen 21. The main filter screen 24 is sleeved on a filter element support 25. The filtration precision of the main filter screen 24 is higher than that of the laminated filter screen 21. Specifically, the filtration precision of the laminated filter screen 21 is 80-100 μm, and the filtration precision of the main filter screen 24 is 30-50 μm. Therefore, the laminated filter screen 21 is coarse filtration, and the main filter screen 24 is fine filtration. The water flow is further filtered by the main filter screen 24 after being filtered by the laminated filter screen 21.

[0049] In the embodiment, the backwashing channel is provided with a backwashing filter screen 6 which is sleeved on a backwashing support 10. The filtration precision of the backwashing filter screen 6 is consistent with or basically consistent with that of the main filter screen 24.

[0050] In this embodiment, sealing rings or gaskets are used to seal the various sealing parts. This is a conventional technique and will not be described in detail.

[0051] This invention has two working states: filtration state and backwashing state. The two working states will be described in detail below.

[0052] When the present invention is in the filtration state, the drain outlet 121 is blocked by the sealing member 7, and each of the first water passage holes 31 of the moving valve plate 3 corresponds to the corresponding second water passage hole 41 of the fixed valve plate 4, thereby opening the switch assembly. At the same time, the active protrusion 32 of the moving valve plate 3 is opposite to and abuts against the driven protrusion 221 of the movable bracket 22, and the spring 5 is in a compressed state, so that the adjacent stacked plates 211 of the stacked filter screen 21 are pressed against each other. Figures 6-8 As shown. Therefore, when water enters through inlet 111, most of the water flows into the raw water chamber 122 through the rotating open switch assembly, and then passes through the stacked filter screen 21 and the main filter screen 24 in sequence before entering the clean water chamber 26, and finally exiting from outlet 112; the remaining water flows through the backwash filter screen 6 and exits from outlet 112, as shown. Figure 9 As shown in the diagram, the arrows indicate the direction of water flow.

[0053] When filter element 2 needs to be flushed, turn the flushing knob 20 counterclockwise (the flushing knob 20 rotates 180° each time), causing the flushing knob 20 to drive the valve stem 8 to rotate. The valve stem 8 then drives the moving valve plate 3 to rotate, causing each of the first water passage holes 31 on the moving valve plate 3 to be offset from the corresponding second water passage holes 41 on the fixed valve plate 4. Figure 11 As shown, the switch assembly is closed. Simultaneously, the active protrusion 32 of the moving valve plate 3 is disengaged from the driven protrusion 221 of the movable bracket 22. Under the restoring force of the spring 5, the movable bracket 22 moves away from the fixed bracket 23 until the active protrusion 32 of the moving valve plate 3 and the driven protrusion 221 of the movable bracket 22 are engaged. Figure 10 As shown. At this time, the adjacent discs 211 of the stacked filter screen 21 are no longer pressed together. When the valve stem 8 rotates, the valve stem 8 also drives the sealing member 7 to rotate, and at the same time the sealing member 7 moves upward, opening the drain port 121. When water enters the inlet 111, because the switch assembly is closed, the water can only flow to the backwash channel, and after being filtered by the backwash filter screen 6, it flows into the clean water chamber 26, and then sequentially washes the main filter screen 24 and the stacked filter screen 21 before being discharged from the drain port 121, as shown. Figure 13 As shown in the diagram, the arrows indicate the direction of water flow. Under the action of water flow, the loosened discs 211 vibrate, causing the intercepted material trapped between the discs 211 to fall off and be discharged, thus achieving the effect of flushing and discharging sewage.

[0054] After the filter core 2 is washed, the washing knob 20 is turned clockwise, the valve rod 8 is reversely rotated by 180°, the movable valve plate 3 is returned to the state of opening the water inlet channel, and at the same time, the valve cover 8 drives the sealing member 7 to return and close the drain outlet 121. At this time, the pre-filter of the application returns to the filtering state.

[0055] Therefore, the pre-filter with backwashing function of the application uses the switch assembly capable of controlling the communication between the water inlet 111 and the raw water cavity 122 to provide the driving force for the movement of the movable support 22, compared with the driving force provided by the water pressure difference in the prior art, the driving force is not affected by the water pressure, and the backwashing process can be ensured to be stable, thereby greatly improving the efficiency and effect of the backwashing of the pre-filter. In addition, the application uses double-layer filter screen progressive filtration, which can greatly improve the filtering effect and effectively protect the main filter screen 24, thereby prolonging the service life of the filter.

[0056] The pre-filter with backwashing function of the application is the same as the prior art in the non-involved parts or can be realized by using the prior art.

[0057] The above embodiments are only used to further illustrate the pre-filter with backwashing function of the application, but the application is not limited to the embodiments, and any simple modification, equivalent change and modification made according to the technical essence of the application to the above embodiments all fall within the protection scope of the technical scheme of the application.

Claims

1. A pre-filter with backwashing function, comprising a housing part, a filter core, the housing part being provided with a water inlet, a water outlet and a blowdown outlet, the filter core being loaded into the housing part and cooperating with the housing part to form a raw water cavity communicating with the blowdown outlet and a purified water cavity communicating with the water outlet, a water inlet channel being provided between the water inlet and the raw water cavity, a backwashing channel being provided between the purified water cavity and the water inlet, and a blocking member being provided at the blowdown outlet for opening and closing the blowdown outlet; characterized in that: the filter core comprises a laminated filter screen and movable and fixed supports distributed along the axial direction of the filter core, the laminated filter screen comprising a plurality of laminated sheets cooperated between the movable and fixed supports; the housing part is provided with a switch assembly capable of controlling the opening and closing of the water inlet channel, the switch assembly being capable of driving the movable support to move along the axial direction of the filter core when being opened and / or closed, so as to press or release the plurality of laminated sheets from each other; a backwashing filter screen is provided at the backwashing channel, so that water flowing through the backwashing channel can be prevented from flowing to the water outlet without being filtered in the filtering state. the switch assembly is capable of driving the movable support to move towards the fixed support when being opened, and the switch assembly is capable of releasing the movable support when being closed, and the movable support is capable of moving away from the fixed support under the action of a restoring member cooperated with the fixed support and / or the housing part. the switch assembly comprises a movable valve plate rotatably provided on the water inlet channel and a fixed valve plate fixed on the water inlet channel, the movable valve plate being provided with a first water passing hole, the fixed valve plate being provided with a second water passing hole, the movable valve plate being cooperated with the fixed valve plate, and the movable valve plate being driven to rotate by a driving member, so that the first water passing hole and the second water passing hole are corresponded or staggered, and the movable valve plate is capable of driving or releasing the movable support by rotating.

2. The pre-filter with back-flushing function according to claim 1, characterized in that: the movable valve plate is provided with a plurality of driving convex portions distributed along the circumferential direction thereof, the movable support is provided with a plurality of driven convex portions distributed along the circumferential direction thereof, and the movable valve plate is capable of driving the driving convex portions to be opposite to or staggered with the driven convex portions by rotating.

3. The pre-filter with back-flushing function according to claim 1 or 2, characterized in that: the driving member is a valve rod, the valve rod being rotatably connected to the housing part about the axis thereof and being opposite to the movable valve plate, one end of the valve rod extending out of the housing part and being provided with a backwashing knob, and the other end of the valve rod penetrating through the purified water cavity and being connected to the blocking member, so that the valve rod is capable of driving the blocking member to open or close the blowdown outlet by rotating.

4. The pre-filter with back-flushing function according to claim 3, characterized in that: the blocking member is capable of rotating with the valve rod and being sleeved on the other end of the valve rod in a manner capable of moving axially relative to the valve rod, and the blocking member is provided with external threads, the external threads being threadedly connected with internal threads of a fixed sleeve fixed in the purified water cavity.

5. The pre-filter with back-flushing function according to claim 3, characterized in that: the number of the first water passing hole and the second water passing hole is equal and is a plurality, the plurality of first water passing holes are distributed along the circumferential direction of the movable valve plate, and the plurality of second water passing holes are distributed along the circumferential direction of the fixed valve plate; the fixed valve plate is provided with a plurality of spiral flow channels distributed along the same rotation direction, the spiral flow channels being inclined water channels or spiral water channels, one end of each spiral flow channel forming the second water passing hole, and the other end of each spiral flow channel forming a water outlet hole capable of laterally discharging water.

6. The pre-filter with back-flushing function according to claim 5, characterized in that: ​ 7. The pre-filter with back-flushing function according to claim 3, characterized in that: ​ 8. The pre-filter with back-flushing function according to claim 2, characterized in that: The reset member comprises an elastic member which is abuttingly fitted between the movable support and the fixed support or the housing part.

9. The pre-filter with back-flushing function according to claim 1, characterized in that: The filter core further comprises a main filter screen inside the laminated filter screen for performing secondary filtration on water passing through the laminated filter screen; the main filter screen has a higher filtration precision than the laminated filter screen, and is sleeved on a filter core support.

10. The pre-filter with back-flushing function according to claim 1 or 9, characterized in that: The backwashing filter screen has a higher filtration precision than the laminated filter screen, and is sleeved on a backwashing support.

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