Inverted pre-filter

Abstract

The utility model relates to an inverted prefilter which comprises a valve casing, a filtering and backwashing mechanism and a filter bottle, the valve casing is provided with a water inlet end, a water outlet end, an upward filter bottle assembling end and a valve casing cavity, the filter bottle is matched and fixed with the filter bottle assembling end, the filtering and backwashing mechanism is arranged in the filter bottle, and a cavity between the filtering mechanism and the filter bottle forms a raw water cavity. The filtering and backwashing mechanism comprises a filtering mechanism and a backwashing mechanism which are coaxially arranged, a flow guide seat is arranged in the valve shell cavity and divides the valve shell cavity into a water inlet end valve shell cavity, a central end valve shell cavity and a water outlet end valve shell cavity, the water inlet end valve shell cavity is communicated with the water inlet end and is provided with a particle pollution discharge control valve, and the central end valve shell cavity is communicated with the water outlet end. The central end valve shell cavity is communicated with a filter screen backwashing blow-down valve through a central blow-down pipe, and the water outlet end valve shell cavity is communicated with the water outlet end. The valve head structure of the inverted pre-filter is more optimized in structure, can be easily matched with an installation occasion, and is provided with a plurality of drainage channels to meet different application modes.

Description

Technical Field

[0001] This utility model relates to an inverted pre-filter, belonging to the technical field of water purification equipment. Background Technology

[0002] The mainstream pre-filters in the current technology are of the bottom-mounted filter bottle type, including: a head unit, a filter bottle connected to the head unit at the top, and a drain ball valve connected to the bottom of the filter bottle. A filter element frame is installed inside the filter bottle, and the filter element is fitted onto the outer wall of the filter element frame. During use, water flows from the inlet of the head unit into the gap between the filter bottle and the filter element, is filtered by the filter element, flows into the center of the filter element frame, and then flows from the center of the filter element frame to the outlet of the head unit. When drainage is required, the drain ball valve at the bottom of the filter bottle is opened.

[0003] In some installation scenarios, the installation of this type of bottom-mounted pre-filter is inconvenient. Therefore, the inverted pre-filter was developed to meet market demand. In addition to the inlet, outlet and filter bottle installation port, the valve head of this type of pre-filter also needs to be equipped with a drain port. That is, the function of the drain ball valve originally located at the bottom of the filter bottle needs to be transferred to the valve head. Therefore, the traditional valve head structure needs to be optimized and adjusted.

[0004] In addition, during the use of a pre-filter, the filter elements need to be cleaned regularly. This is generally achieved through a backwashing mechanism, and the filter is then discharged through the drain port. However, the backwash filter itself also needs to be cleaned and drained regularly. This invention aims to provide an inverted pre-filter with a more optimized structure, easy to match with installation occasions, and multiple drain channels to meet different application modes. Utility Model Content

[0005] One of the purposes of this invention is to address the shortcomings of existing pre-filters and provide an inverted pre-filter with a more optimized structure, easier matching to installation occasions, and multiple drainage channels to meet different application modes.

[0006] The technical solution adopted by this utility model to solve its technical problem is:

[0007] An inverted pre-filter includes a valve housing, a filtration and backwashing mechanism, and a filter bottle. The valve housing has an inlet end, an outlet end, an upward-facing filter bottle assembly end, and a valve housing cavity. The filter bottle is fixed to the filter bottle assembly end. The filtration and backwashing mechanism is located inside the filter bottle, and the cavity between the filtration mechanism and the filter bottle forms a raw water cavity. The filtration and backwashing mechanism includes a filtration mechanism and a backwashing mechanism arranged coaxially. A flow guide seat is provided in the valve housing cavity, which divides the valve housing cavity into an inlet valve housing cavity, a central valve housing cavity, and an outlet valve housing cavity. The inlet valve housing cavity is connected to the inlet end and has a particle discharge channel. The central valve housing cavity is connected to a filter element backwash discharge channel through a central drain pipe. The outlet valve housing cavity is connected to the outlet end. The end of the backwashing mechanism is adapted to the central valve housing cavity. Under the action of pressure difference, the backwashing mechanism can move axially relative to the filtration mechanism to switch between filtration mode and backwashing mode.

[0008] This invention features an inlet, outlet, and upward-facing filter bottle assembly end on the valve head. It also includes two independent drain valves for particle discharge and a backwash discharge channel for the filter element. Essentially, the function of the drain ball valve, originally located at the bottom of the filter bottle, is transferred to the valve head, effectively optimizing the traditional valve head structure. During filtration, raw water flows sequentially from the inlet end and the inlet valve chamber into the raw water chamber between the filter mechanism and the filter bottle. After filtration, it flows out through the central valve chamber, the outlet valve chamber, and the outlet end. Large particles accumulate in the inlet valve chamber and can be directly discharged through the particle discharge channel. In backwash mode, wastewater from the backwash of the filter element enters the raw water chamber, which then flows through the central drain pipe to the filter element backwash discharge channel. The optimized structure facilitates installation and provides multiple discharge channels to meet different application modes.

[0009] Preferably, the filtration mechanism includes a filter frame and a filter element. The filter frame includes a frame body, an inlet end cap, and a frame bottom cap. The inlet end cap has a raw water inlet channel and a backwash frame assembly port, and the frame bottom cap has a backwash frame assembly port. The backwashing mechanism includes a backwash frame and a backwash filter element. The backwash frame is divided into a backwashing section, an assembly section, and a drive section. The assembly section is inserted into the frame body. The backwashing section and the drive section extend from the backwash frame assembly port. The backwash filter element is fixed to the backwashing section. The backwashing section is located in the central valve housing cavity and is slidably sealed to the central valve housing cavity. The backwashing section also has a sealing... The sealing part allows the backwashing mechanism to close or open the raw water inlet channel during axial movement. The drive section is fixedly equipped with a backwash cover, which has backwash water holes. It also includes an elastic reset member, located between the frame body and the backwash frame, or between the backwash cover and the inner wall of the filter bottle. Under the pressure difference on both sides of the backwash cover, the backwashing mechanism is driven to move axially relative to the filtration mechanism. Moving upwards closes the raw water inlet channel, and the backwashing section protrudes from the central valve housing cavity, entering the backwashing mode. Moving downwards opens the raw water inlet channel, and the backwashing section extends into the central valve housing cavity, entering the filtration mode.

[0010] Preferably, there is a pressure difference ΔP on both sides of the backwash cover. When ΔP ≥ 0 and the force corresponding to ΔP is greater than the reaction force of the elastic reset member, the elastic reset member is stretched or compressed, and the backwash mechanism moves axially upward against the direction of sewage flow. When the force corresponding to ΔP is less than the reaction force of the elastic reset member, the elastic reset member is reset, and the backwash mechanism moves axially downward in the direction of sewage flow. The pressure difference ΔP is adjusted by opening and closing the backwash discharge channel of the filter element.

[0011] Preferably, the outlet valve housing cavity is further provided with a backwashing filtration cavity, which has a backwashing filter element flushing and discharge channel, and the central valve housing cavity has a backwashing filter element flushing channel. In the backwashing mode of the backwashing filter, the wastewater that backwashes the backwashing filter enters the outlet valve housing cavity and is discharged through the backwashing filter element flushing and discharge channel, thus expanding the multiple discharge channels to meet different application modes.

[0012] Preferably, the filter bottle assembly end is provided with a quick-release structure for assembling the filter bottle. The quick-release structure is detachable and includes a screw-in structure and a snap-fit ​​structure. This quick-release structure facilitates user installation, filter bottle replacement and maintenance, and also allows for easy disassembly and cleaning when impurities remain and cause blockage inside the valve head.

[0013] Preferably, the filter frame is a filter mesh frame, and the filter element is a filter mesh or PP cotton; the backwash frame is a backwash filter mesh frame, and the backwash filter element is a filter mesh or PP cotton; or, the filter frame and the backwash frame are both stacked frame frames, and the filter element and the backwash filter element are both stacked filter discs.

[0014] Preferably, the flow guide seat has a buffer wall in the valve shell cavity at the water inlet end, and a buffer zone is formed below the buffer wall. The buffer wall and buffer zone allow large particles of impurities to settle as they pass through, and then be discharged via the particle discharge channel, delaying clogging of the filter element and improving the performance of the pre-filter.

[0015] Preferably, the buffer wall includes a blocking section, an oblique flow guide section, and a vertical flow guide section, with the junction of the blocking section, the oblique flow guide section, and the vertical flow guide section forming an arc transition. By changing the water flow direction and velocity, the effect of large particle impurity deposition is improved, further enhancing the performance of the pre-filter and extending its service life.

[0016] Preferably, the flow guide seat has a flow guide pipe in the valve shell cavity at the water outlet, and the flow guide pipe has a transition zone. By setting the flow guide pipe and the transition zone, the purified water at the water outlet can flow out stably, avoiding large fluctuations in flow rate and velocity.

[0017] Preferably, the transition zone is an arc transition, and the axial direction of the guide pipe is consistent with the axial direction of the water outlet. The consistent arc transition zone and axial direction can reduce the resistance to the outflow of purified water, allowing the purified water to flow out stably from the outlet and avoiding large fluctuations in flow rate and velocity.

[0018] Preferably, the guide seat is integrally molded from an inert material, which is rubber or plastic, or at least the side in contact with water is coated with an inert material, which is plastic, rubber, or ceramic.

[0019] Preferably, the flow guide seat is provided with an assembly part in the central valve housing cavity, the assembly part is adapted to the backwash section of the backwashing filtration mechanism of the inverted pre-filter, and the inner cavity of the filtration and backwashing mechanism can communicate with the central valve housing cavity.

[0020] Preferably, the inlet end, outlet end, and filter bottle assembly end are provided with isolation bushings. The isolation bushings are made of inert material and include an inlet end isolation bushing, an outlet end isolation bushing, and an assembly end isolation bushing. They are integrally injection molded from plastic or rubber material. Alternatively, at least one side of the isolation bushing in contact with water is coated with an inert material, which is plastic, rubber, or ceramic.

[0021] The beneficial effects of this utility model are as follows: This utility model realizes the setting of an inlet end, an outlet end, and an upward-facing filter bottle assembly end on the valve head. It also sets two independent drain valves for particle discharge and a backwash discharge channel for the filter element. In other words, the function of the drain ball valve originally located at the lower end of the filter bottle is transferred to the valve head, effectively optimizing and adjusting the traditional valve head structure. During filtration, raw water flows sequentially from the inlet end and the inlet end valve shell cavity into the raw water cavity between the filter mechanism and the filter bottle. After filtration, it flows out through the central end valve shell cavity, the outlet end valve shell cavity, and the outlet end. Large particle impurities accumulate in the inlet end valve shell cavity and can be directly discharged through the particle discharge channel. In the backwash mode, the wastewater from the backwash of the filter element enters the raw water cavity, and the raw water cavity flows through the central drain pipe to the backwash discharge channel of the filter element for discharge. The structure is more optimized, easy to match the installation occasion, and has multiple discharge channels to meet different application modes. In the backwash mode of the backwash filter, the wastewater that backwashes the backwash filter enters the outlet valve chamber and is discharged through the backwash filter element's flushing and sewage discharge channel, thus expanding the sewage discharge channels to meet different application modes. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of this utility model;

[0024] Figure 2 This is a schematic diagram of the structure of this utility model;

[0025] Figure 3 This is a cross-sectional view of the present invention (in filtered state);

[0026] Figure 4 This is a cross-sectional view of the present invention (particles arranged in a straight line);

[0027] Figure 5 This is a cross-sectional view of the present invention (backwashing filter element flushing and sewage discharge);

[0028] Figure 6 This is a cross-sectional view of the present invention showing direct discharge of particles (backwashing and sewage discharge of the filter element);

[0029] Figure 7 This is an exploded view of the present invention;

[0030] Figure 8 yes Figure 7 A partial exploded view.

[0031] In the diagram: 1. Valve housing; 11. Inlet end; 12. Outlet end; 13. Filter bottle assembly end; 14. Valve housing cavity; 14a. Inlet end valve housing cavity; 14b. Central end valve housing cavity; 14c. Outlet end valve housing cavity; 14d. Backwashing filter cavity; 2. Flow guide seat; 21. Buffer wall; 22. Buffer zone; 23. Flow guide pipe; 24. Transition zone; 3. Particle discharge channel; 4. Central discharge pipe; 5. Filter element backwash discharge channel; 6. Backwashing filter element flushing discharge channel; 7. Filter bottle; 8. Filter frame; 81. Inlet end cover; 82. Frame bottom cover; 9. Filter element; 10. Backwashing frame; 10a. Backwashing filter element; 10b. Backwashing cover; 10c. Sealing part; A. Elastic reset element. Detailed Implementation

[0032] The embodiments of this utility model are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0033] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0034] In the description of this utility model, the use of "first" and "second" is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features or the order of the technical features.

[0035] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0036] Example 1

[0037] like Figure 1-8As shown, an inverted pre-filter includes a valve housing 1, a filtration and backwashing mechanism, and a filter bottle 7. The valve housing 1 has an inlet end 11, an outlet end 12, an upward-facing filter bottle assembly end 13, and a valve housing cavity 14. The filter bottle 7 is fixedly fitted to the filter bottle assembly end 13. The filtration and backwashing mechanism is located inside the filter bottle 7, and the cavity between the filtration mechanism and the filter bottle 7 forms a raw water cavity. The filtration and backwashing mechanism includes a filtration mechanism and a backwashing mechanism arranged coaxially. The valve housing cavity 14 is characterized by having a flow guide seat 2, which divides the valve housing cavity 14 into... The filter housing is divided into an inlet valve housing 14a, a central valve housing 14b, and an outlet valve housing 14c. The inlet valve housing 14a is connected to the inlet end 11 and is provided with a particle discharge channel 3. The central valve housing 14b is connected to the filter element backwash discharge channel 5 through a central drain pipe 4. The outlet valve housing 14c is connected to the outlet end 12. The end of the backwashing mechanism is adapted to the central valve housing 14b. Under the action of pressure difference, the backwashing mechanism can move axially relative to the filter mechanism to switch between the filtration mode and the backwashing mode.

[0038] This invention features an inlet, outlet, and upward-facing filter bottle assembly end on the valve head. It also includes two independent drain valves for particle discharge and a backwash discharge channel for the filter element. Essentially, the function of the drain ball valve, originally located at the bottom of the filter bottle, is transferred to the valve head, effectively optimizing the traditional valve head structure. During filtration, raw water flows sequentially from the inlet end and the inlet valve chamber into the raw water chamber between the filter mechanism and the filter bottle. After filtration, it flows out through the central valve chamber, the outlet valve chamber, and the outlet end. Large particles accumulate in the inlet valve chamber and can be directly discharged through the particle discharge channel. In backwash mode, wastewater from the backwash of the filter element enters the raw water chamber, which then flows through the central drain pipe to the filter element backwash discharge channel. The optimized structure facilitates installation and provides multiple discharge channels to meet different application modes.

[0039] Specifically, the filtration mechanism includes a filter frame 8 and a filter element 9. The filter frame 8 includes a frame body, an inlet end cap 81, and a frame bottom cap 82. The inlet end cap 81 has a raw water inlet channel and a backwash frame assembly port, and the frame bottom cap 82 has a backwash frame assembly port. The backwash mechanism includes a backwash frame 10 and a backwash filter element 10a. The backwash frame 10 is divided into a backwash section, an assembly section, and a drive section. The assembly section is inserted into the frame body. The backwash section and the drive section extend from the backwash frame assembly port. The backwash filter element 10a is fixed to the backwash section. The backwash section is located in the central valve housing cavity 14b and is slidably sealed to the central valve housing cavity 14b. The backwash section also has a sealing... The sealing part 10c can close or open the raw water inlet channel when the backwashing mechanism moves axially. The drive section is fixedly provided with a backwash cover 10b, which has a backwash water hole. It also includes an elastic reset member A, which is located between the skeleton body and the backwash skeleton, or between the backwash cover 10b and the inner wall of the filter bottle 7. Under the pressure difference on both sides of the backwash cover 10b, the backwashing mechanism is driven to move axially relative to the filtration mechanism. When it moves upward, it closes the raw water inlet channel, and the backwashing section is exposed from the central end valve shell cavity 14b, entering the backwashing mode. When it moves downward, it opens the raw water inlet channel, and the backwashing section extends into the central end valve shell cavity 14b, entering the filtration mode.

[0040] In this embodiment, there is a pressure difference ΔP on both sides of the backwash cover 10b. When ΔP ≥ 0 and the force corresponding to ΔP is greater than the reaction force of the elastic reset member, the elastic reset member A is stretched or compressed, and the backwash mechanism moves axially upward against the direction of sewage flow. When the force corresponding to ΔP is less than the reaction force of the elastic reset member A, the elastic reset member A is reset, and the backwash mechanism moves axially downward in the direction of sewage flow. The pressure difference ΔP is adjusted by opening and closing the backwash discharge channel 5 of the filter element.

[0041] In this embodiment, the outlet valve housing 14c is further provided with a backwashing filtration chamber 14d, which has a backwashing filter element flushing and drainage channel 6. The central valve housing 14b is provided with a backwashing filter element flushing channel. In the backwashing mode of the backwashing filter, the wastewater that backwashes the backwashing filter enters the outlet valve housing and is discharged through the backwashing filter element flushing and drainage channel 6, thus expanding the multiple drainage channels to meet different application modes. The filter bottle assembly end 13 is provided with a quick-installation structure for assembling the filter bottle. The quick-installation structure is detachable and includes a screw connection and a snap-fit ​​connection. This quick-installation structure facilitates user installation, filter bottle replacement and maintenance, and easy disassembly and cleaning when impurities remain and clog the valve head.

[0042] In this embodiment, the filter frame is a filter mesh frame, and the filter element is a filter mesh or PP cotton; the backwash frame is a backwash filter mesh frame, and the backwash filter element is a filter mesh or PP cotton; or, both the filter frame and the backwash frame are stacked frame frames, and both the filter element and the backwash filter element are stacked filter discs. More specifically, the flow guide seat 2 has a buffer wall 21 in the inlet valve housing 14a, and a buffer zone 22 is formed below the buffer wall 21. The buffer wall and buffer zone allow large particles of impurities to deposit as they pass through, and discharge them through the particle discharge channel 3, delaying clogging of the filter element and improving the performance of the pre-filter. The buffer wall 21 includes a blocking part, an oblique flow guide part, and a vertical flow guide part, and the junction of the blocking part, the oblique flow guide part, and the vertical flow guide part is a rounded transition. By changing the direction and velocity of the water flow, the deposition effect of large particles of impurities is improved, further improving the performance of the pre-filter and extending its service life. The flow guide seat 2 has a flow guide pipe 23 in the outlet valve housing 14c, and the flow guide pipe 23 has a transition zone 24. By setting up a guide pipe and a transition zone, the purified water at the outlet can flow out steadily, avoiding large fluctuations in flow rate and velocity.

[0043] In this embodiment, the transition zone 24 is an arc transition, and the axial direction of the guide pipe 23 is consistent with the axial direction of the water outlet 12. The consistent arc transition zone and axial direction can reduce the resistance to the outflow of purified water, allowing the purified water to flow out stably from the water outlet and avoiding large fluctuations in flow rate and velocity.

[0044] In this embodiment, to improve the environmental friendliness of the valve head, the flow guide seat is integrally molded with an inert material, which is rubber or plastic, or at least the side in contact with water is coated with an inert material, which is plastic, rubber or ceramic.

[0045] Specifically, the guide seat 2 has an assembly part located in the central valve housing cavity 14b. The assembly part is adapted to the backwash section of the backwashing filtration mechanism of the inverted pre-filter, and the inner cavity of the filtration and backwashing mechanism is connected to the central valve housing cavity 14b. The inlet end 11, outlet end 12, and filter bottle assembly end 13 are provided with isolation bushings. The isolation bushings are made of inert material and include an inlet end isolation bushing, an outlet end isolation bushing, and an assembly end isolation bushing. They are integrally injection molded from plastic or rubber material; or the isolation bushing has an inert material coating on at least one side that is in contact with water. The inert material is plastic, rubber, or ceramic.

[0046] This invention features an inlet, outlet, and upward-facing filter bottle assembly end on the valve head. It also includes two independent drain valves for particle discharge and a backwash discharge channel for the filter element. Essentially, the function of the drain ball valve, originally located at the bottom of the filter bottle, is transferred to the valve head, effectively optimizing the traditional valve head structure. During filtration, raw water flows sequentially from the inlet end and the inlet valve chamber into the raw water chamber between the filter mechanism and the filter bottle. After filtration, it flows out through the central valve chamber, the outlet valve chamber, and the outlet end. Large particles accumulate in the inlet valve chamber and can be directly discharged through the particle discharge channel. In backwash mode, wastewater from the backwash of the filter element enters the raw water chamber, which then flows through the central drain pipe to the filter element backwash discharge channel. The optimized structure facilitates installation and provides multiple discharge channels to meet different application modes. In the backwash mode of the backwash filter, the wastewater that backwashes the backwash filter enters the outlet valve chamber and is discharged through the backwash filter element's flushing and sewage discharge channel, thus expanding the sewage discharge channels to meet different application modes.

[0047] The embodiments described above are merely preferred solutions of this utility model and are not intended to limit this utility model in any way. Other variations and modifications are possible without departing from the technical solutions described in the claims.

Claims

1. An inverted pre-filter, comprising a valve housing (1), a filtration and backwashing mechanism, and a filter bottle (7), wherein the valve housing (1) is provided with an inlet end (11), an outlet end (12), an upward-facing filter bottle assembly end (13), and a valve housing cavity (14), the filter bottle (7) is fixedly fitted to the filter bottle assembly end (13), the filtration and backwashing mechanism is disposed inside the filter bottle (7), and the cavity between the filtration mechanism and the filter bottle (7) constitutes a raw water cavity, wherein the filtration and backwashing mechanism comprises a filtration mechanism and a backwashing mechanism arranged coaxially, characterized in that: The valve shell cavity (14) is provided with a flow guide seat (2), which divides the valve shell cavity (14) into a water inlet end valve shell cavity (14a), a central end valve shell cavity (14b) and a water outlet end valve shell cavity (14c). The water inlet end valve shell cavity (14a) is communicated with the water inlet end (11) and is provided with a particle blowdown channel (3). The central end valve shell cavity (14b) is communicated through a central blowdown pipe (4) and is provided with a backwashing blowdown channel (5) through a filter element (9). The water outlet end valve shell cavity (14c) is communicated with the water outlet end (12). The end of the backwashing mechanism is adapted to the central end valve shell cavity (14b), and the backwashing mechanism can move axially relative to the filtering mechanism under the action of a pressure difference to switch between filtering mode and backwashing mode.

2. The inverted prefilter of claim 1, wherein: The filtering mechanism includes a filtering framework (8) and a filter element (9). The filtering framework (8) includes a framework body, a water inlet end cover (81) and a framework bottom cover (82). The water inlet end cover (81) is provided with a raw water inlet channel and a backwashing framework assembly opening. The framework bottom cover (82) is provided with a backwashing framework assembly opening. The backwashing mechanism includes a backwashing framework (10) and a backwashing filter element (10a). The backwashing framework (10) is divided into a backwashing section, an assembly section and a driving section. The assembly section is inserted into the framework body. The backwashing section and the driving section extend out of the backwashing framework assembly opening. The backwashing filter element (10a) is fixed to the backwashing section. The backwashing section is located in the central end valve shell cavity (14b) and is in sliding sealing connection with the central end valve shell cavity (14b). The backwashing section is also provided with a sealing part (10c). When the backwashing mechanism moves axially, the sealing part (10c) can close or open the raw water inlet channel. The driving section is fixedly provided with a backwashing cover (10b) provided with a backwashing water hole. An elastic return member (A) is arranged between the framework body and the backwashing framework (10) or between the backwashing cover (10b) and the inner wall of the filter bottle. Under the action of the pressure difference on both sides of the backwashing cover (10b), the backwashing mechanism is driven to move axially relative to the filtering mechanism. When moving upward, the raw water inlet channel is closed, the backwashing section is exposed from the central end valve shell cavity (14b), the backwashing mode is entered, and when moving downward, the raw water inlet channel is opened, the backwashing section is inserted into the central end valve shell cavity (14b), and the filtering mode is entered.

3. The inverted prefilter of claim 2, wherein: There is a pressure difference △P on both sides of the backwashing cover (10b), and △P≥0. When the corresponding force of △P is greater than the counterforce of the elastic return member (A), the elastic return member (A) is stretched or compressed, and the backwashing mechanism moves axially in the opposite direction of the blowdown water flow. When the corresponding force of △P is less than the counterforce of the elastic return member (A), the elastic return member (A) returns, and the backwashing mechanism moves axially in the direction of the blowdown water flow. The opening and closing of the backwashing blowdown channel (5) through the filter element (9) adjusts the size of the pressure difference △P.

4. An inverted pre-filter according to claim 2 or 3, characterised in that: The water outlet end valve shell cavity (14c) is also provided with a backwashing filter cavity (14d) provided with a backwashing filter element flushing and sewage discharge channel (6), and the central end valve shell cavity (14b) is provided with a backwashing filter element flushing channel; the filter bottle assembly end (13) is provided with a quick assembly structure for assembly of the filter bottle, and the quick assembly structure adopts a detachable structure including a screwing structure and a clamping structure.

5. The inverted prefilter of claim 4, wherein: The filter skeleton (8) is a filter screen skeleton, the filter element (9) is a filter screen or PP cotton, the backwashing skeleton (10) is a backwashing filter screen skeleton, and the backwashing filter element (10a) is a filter screen or PP cotton; or the filter skeleton (8) and the backwashing skeleton (10) are both laminated skeletons, and the filter element (9) and the backwashing filter element (10a) are both filter laminations.

6. The inverted prefilter of claim 1 or 2 or 3, wherein: The flow guide base (2) is provided with a buffer wall (21) in the water inlet end valve shell cavity (14a), and a buffer zone (22) is formed below the buffer wall (21).

7. The inverted prefilter of claim 6, wherein: The buffer wall (21) includes a blocking portion, an oblique flow guide portion and a vertical flow guide portion, and the junction of the blocking portion, the oblique flow guide portion and the vertical flow guide portion is in a circular arc transition.

8. The inverted prefilter of claim 7, wherein: The flow guide base (2) is provided with a flow guide pipe (23) in the water outlet end valve shell cavity (14c), and the flow guide pipe (23) is provided with a transition zone (24); the transition zone (24) is in a circular arc transition, and the axial direction of the flow guide pipe (23) is consistent with the axial direction of the water outlet end (12).

9. The inverted prefilter of claim 1 or 2 or 3, wherein: The flow guide base is integrally formed by using inert materials, the inert materials are rubber or plastic, or at least one side in contact with water is provided with an inert material coating, the inert materials are plastic, rubber or ceramic; the water inlet end (11), the water outlet end (12) and the filter bottle assembly end (13) are provided with isolation bushings, the isolation bushings are processed by using inert materials, the isolation bushings include a water inlet end isolation bushing, a water outlet end isolation bushing and an assembly end isolation bushing, and are integrally injection molded by using plastic or rubber materials; or at least one side in contact with water of the isolation bushings is provided with an inert material coating, and the inert materials are plastic, rubber or ceramic.

10. The inverted prefilter of claim 1 or 2 or 3, wherein: The flow guide base (2) located in the central end valve shell cavity (14b) is provided with an assembly portion adapted to a backwashing section of a backwashing filter mechanism of an inverted front filter, and an inner cavity of the filter and the backwashing mechanism can communicate with the central end valve shell cavity (14b).

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