Shallow sand filter with protection function

Abstract

The invention discloses a shallow sand filter with a protection function, which comprises a filter tank main body, a liquid inlet pipe is mounted at the inner top of the filter tank main body, and a liquid discharge pipe is mounted at the inner bottom of the filter tank main body; the gravel filtering mechanism is used for filtering a water body and comprises a transverse plate fixedly connected between the front inner wall and the rear inner wall of the bottom part of the filtering tank main body, the upper end of the transverse plate is rotationally connected with a rotating shaft, the upper end of the rotating shaft is fixedly connected with a conical barrel, and the conical barrel is filled with gravel; the upper end face of the gravel is lower than the middle of the conical barrel, and a plurality of filtering round openings are formed in the inner bottom of the conical barrel. In the use process of the filter, when backwashing operation is executed, impurities tightly adhered to the gravel can also be removed, follow-up independent cleaning is not needed, the follow-up maintenance cost is reduced, in addition, discharged waste water can be treated, and waste of water resources is reduced.

Description

Technical Field

[0001] The invention relates to the field of filters, in particular to a shallow sand filter with a protective function. Background Art

[0002] Shallow sand filters with protective functions usually refer to those devices that integrate automatic flushing, backwashing and other mechanisms, and can self-clean, protect and maintain high-efficiency filtering performance during operation. Such filters are widely used in various industrial and civil fields, such as electricity, petrochemicals, metallurgy, textiles, papermaking, food and beverages, municipal water supply, etc. Shallow sand filters use quartz sand and other filter materials to intercept and remove impurities such as suspended matter, organic matter, colloidal particles, microorganisms, etc. in raw water under a certain pressure, thereby achieving the purpose of purifying water quality; When performing backwashing procedures, traditional shallow sand filters are often limited to removing impurities that are loosely attached to the surface of the filter material. However, they are unable to remove stubborn impurities that are tightly adhered to the sand particles. In the long run, this not only affects the continuous and efficient operation of the filter, but also forces operators to regularly perform tedious sand and gravel removal and separate fine cleaning operations, greatly increasing the complexity and cost of maintenance; in addition, the wastewater generated during the traditional backwashing process is often discharged directly into the external environment without effective treatment, which is not only a huge waste of precious water resources, but also may cause unnecessary burdens on the environment. Especially at the moment when water resources are becoming increasingly tight, this treatment method is even more inappropriate, so how to solve these problems needs to be considered. Summary of the invention

[0003] The purpose of the present invention is to solve the shortcomings existing in the prior art and to propose a shallow sand filter with a protective function. During the use of the filter, when performing the backwash operation, the impurities that are more tightly adhered to the sand and gravel can also be removed without the need for subsequent separate cleaning, thereby reducing the cost of subsequent maintenance. In addition, the discharged wastewater can also be treated to reduce the waste of water resources.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: A shallow sand filter with a protective function comprises a filter tank body, a liquid inlet pipe is installed on the inner top of the filter tank body, and a liquid discharge pipe is installed on the inner bottom of the filter tank body; a sand and gravel filtering mechanism, which is used to filter the water body, and the sand and gravel filtering mechanism comprises a transverse plate fixedly connected between the front and rear inner walls of the bottom part of the filter tank body, the upper end of the transverse plate is rotatably connected to a rotating shaft, the upper end of the rotating shaft is fixedly connected to a conical cylinder, the conical cylinder is filled with sand and gravel, the upper end surface height of the sand and gravel is lower than the height of the middle part of the conical cylinder, and the inner bottom of the conical cylinder is A plurality of filter circular openings are provided; a backwashing mechanism, the backwashing mechanism comprising a water tank fixedly connected to the left side of the filter tank body, a water storage chamber is arranged inside the water tank, a piston cylinder is fixedly connected to the right side of the filter tank body, the inner bottom of the piston cylinder is connected to the inner bottom space of the water storage chamber through a first one-way tube, the inner bottom space of the piston cylinder is connected to a second one-way tube, and the second one-way tube is connected to the inner bottom space of the filter tank body; a driving mechanism, the driving mechanism is used to drive the backwashing mechanism to operate; a self-cleaning mechanism, the self-cleaning mechanism is used to comprehensively clean the sand and gravel.

[0005] Preferably, the driving mechanism includes a dual-axis motor installed on the right side of the filter tank body, the right end output shaft of the dual-axis motor is fixedly connected to a rotating plate, the eccentric part of the rotating plate is rotatably connected to a connecting rod, and a second piston plate that can slide up and down is provided in the piston cylinder, and the upper end of the second piston plate is rotatably connected to the other end of the connecting rod.

[0006] Preferably, one-way valves are installed inside the first one-way tube and the second one-way tube. The one-way valve in the first one-way tube flows in a one-way direction from the water storage chamber into the bottom space in the piston cylinder, and the one-way valve in the second one-way tube flows in a one-way direction from the bottom space in the piston cylinder into the bottom of the filter tank body.

[0007] Preferably, the self-cleaning mechanism includes a second bevel gear mounted on the rotating shaft, the left end output shaft of the dual-shaft motor extends to the inside of the filter tank body and is installed with a first bevel gear, and the first bevel gear is meshed with the second bevel gear.

[0008] Preferably, a support mesh plate is horizontally arranged on the inner bottom of the filter tank body, and the support mesh plate is fixedly connected to the inner wall of the filter tank body, and the upper end of the support mesh plate is symmetrically fixedly connected to two electric telescopic rods, and the telescopic ends of the two electric telescopic rods are commonly fixedly connected to a support tube, the upper end surface of the support tube is higher than the conical tube, the upper end surface of the support tube passes through the gap between the conical tube and the inner wall of the filter tank body, and is slidably connected, the inner bottom of the support tube is provided with a circular opening, and the rotating shaft passes through the circular opening, and the inner bottom of the support tube is symmetrically fixedly connected to two abutting hemispheres, and four sliding grooves are evenly spaced on the inner side wall of the conical tube, and a slidable shaking plate is arranged in each of the sliding grooves, and a side of each of the shaking plates away from the middle of the conical tube is elastically connected to the inner wall of the sliding groove through a plurality of shaking springs, and a round head rod is fixedly connected to the side of each of the shaking plates away from the middle of the conical tube, and the other end of each of the round head rods passes through the inner wall of the corresponding sliding groove, and is slidably connected, and a plurality of the round head rods cooperate with the two abutting hemispheres.

[0009] Preferably, a wastewater outlet is provided on the left inner wall of the filter tank body, a separation groove is provided at the upper end of the water tank, the inner bottom of the separation groove is connected with the inside of the water storage chamber through a plurality of water openings, the water storage chamber is filled with water, a water collecting cover is installed on the inner top of the water storage chamber, and a downpipe is installed on the inner bottom of the water collecting cover.

[0010] Preferably, a normally closed solenoid valve is installed in the downpipe, a normally open solenoid valve is installed inside the inlet pipe and the outlet pipe, and a first liquid level sensor is installed on the right inner wall of the filter tank body, and the first liquid level sensor is electrically connected to the dual-axis motor and two normally open solenoid valves.

[0011] Preferably, a negative pressure cylinder is fixedly connected to the left side of the water tank, a vent hole is opened on the left inner wall of the negative pressure cylinder, the right side of the negative pressure cylinder is connected to the inside of the water storage chamber, and a first piston plate that can slide left and right is provided in the negative pressure cylinder, and the left side of the first piston plate is elastically connected to the left inner wall of the negative pressure cylinder through a restoring spring.

[0012] Preferably, a placement plate is fixedly connected to the right side of the filter tank body, and a sand and gravel discharge outlet is opened on the right side wall of the filter tank body.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. After impurity blockage occurs, the backwashing procedure is automatically triggered. This process does not require manual intervention, which reduces the complexity of operation and improves work efficiency.

[0014] 2. The waste water generated during the backwashing process is recycled into the water storage chamber through the negative pressure principle, which reduces the waste of water resources and embodies the design concept of environmental protection and energy saving.

[0015] 3. During the backwashing process, the sand and gravel will move back and forth and collide. During the collision of the sand and gravel, the impurities tightly adhering to the surface can fall off. In the process, the gaps between the sand and gravel as a whole become larger, so that the impurities mixed in the sand and gravel can also be carried away by the water flow, making the overall cleaning effect excellent.

[0016] 4. After a single recoil is completed, the sand and gravel will be redistributed, so that the service life of the entire sand and gravel will be evenly consumed, avoiding the situation where the service life of the top layer of sand and gravel is low and the service life of the bottom layer of sand and gravel is high.

[0017] 5. By utilizing the rotation operation of the conical cylinder, when sand and gravel need to be replaced, the conical cylinder will allow the internal sand and gravel to be discharged from the sand and gravel discharge port under the action of centrifugal force, thereby realizing the sand and gravel discharge operation. After the sand and gravel are discharged, an appropriate amount of new sand and gravel can be added from the sand and gravel adding port, which greatly facilitates the operation of replacing sand and gravel.

[0018] In summary, the present invention not only improves the filtering efficiency and cleaning effect of the shallow sand filter, but also achieves the goals of energy saving and consumption reduction and environmental protection. At the same time, it allows the sand and gravel to be consumed evenly as a whole, reducing the actual maintenance time and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of a shallow sand filter with protective function proposed by the present invention; Figure 2 for Figure 1 Schematic diagram of the left side perspective; Figure 3 for Figure 2 A schematic cross-sectional structure diagram of ; Figure 4 It is a structural schematic diagram of the self-cleaning mechanism; Figure 5 for Figure 4 A schematic cross-sectional structure diagram of ; Figure 6 for Figure 5 A magnified image of point A; Figure 7 This is a top view of the sand and gravel discharge outlet; Figure 8 It is a structural schematic diagram of the backwashing mechanism; Fig. 9 for Figure 8 Schematic diagram of the cross-sectional structure.

[0020] In the figure: 1 filter tank body, 2 liquid inlet pipe, 3 sand and gravel adding port, 4 water tank, 5 negative pressure cylinder, 6 separation tank, 7 sand and gravel discharge port, 8 placement plate, 9 dual-axis motor, 10 rotating plate, 11 connecting rod, 12 piston cylinder, 13 first one-way pipe, 14 second one-way pipe, 15 wastewater discharge port, 16 water storage chamber, 17 liquid discharge pipe, 18 support mesh plate, 19 electric telescopic rod, 20 support cylinder, 21 first liquid level sensor, 22 conical cylinder, 23 filter circular port, 24 horizontal plate, 25 rotating shaft, 26 second bevel gear, 27 first bevel gear, 28 slide, 29 shaking plate, 30 round head rod, 31 shaking spring, 32 moving hemisphere, 33 first piston plate, 34 recovery spring, 35 water collecting cover, 36 liquid drop pipe, 37 water outlet, 38 second piston plate. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0022] Reference Figure 1-Figure 9 A shallow sand filter with protective function, comprising a filter tank body 1, a liquid inlet pipe 2 is installed at the inner top of the filter tank body 1, a liquid discharge pipe 17 is installed at the inner bottom of the filter tank body 1, the liquid inlet pipe 2 is connected to an external water supply part, and the other end of the liquid discharge pipe 17 is connected to a subsequent fine processing device; As an embodiment of the present invention, a sand and gravel filtering mechanism is also included, which is used to filter the water body. The sand and gravel filtering mechanism includes a horizontal plate 24 fixedly connected between the front and rear inner walls of the bottom part of the filter tank body 1, and the upper end of the horizontal plate 24 is rotatably connected to a rotating shaft 25, and the upper end of the rotating shaft 25 is fixedly connected to a conical cylinder 22, and the conical cylinder 22 is filled with sand and gravel. The height of the upper end surface of the sand and gravel is lower than the height of the middle part of the conical cylinder 22, and the inner bottom of the conical cylinder 22 is provided with a plurality of filtering circular openings 23; As an embodiment of the present invention, it also includes a backwashing mechanism, which includes a water tank 4 fixedly connected to the left side of the filter tank body 1, a water storage chamber 16 is arranged inside the water tank 4, and a sealable water inlet (not shown) is also installed on the rear side of the water storage chamber 16, and a piston cylinder 12 is fixedly connected to the right side of the filter tank body 1, and the inner bottom of the piston cylinder 12 is communicated with the inner bottom space of the water storage chamber 16 through a first one-way tube 13, and the inner bottom space of the piston cylinder 12 is communicated with the second one-way tube 14, and the second one-way tube 14 is communicated with the inner bottom space of the filter tank body 1, and one-way valves are installed inside the first one-way tube 13 and the second one-way tube 14, and the one-way valve in the first one-way tube 13 flows in a one-way direction from the inside of the water storage chamber 16 to the inner bottom space of the piston cylinder 12, and the one-way valve in the second one-way tube 14 flows in a one-way direction from the inner bottom space of the piston cylinder 12 to the inner bottom of the filter tank body 1; As an embodiment of the present invention, a driving mechanism is also included, and the driving mechanism is used to drive the backwashing mechanism to operate. The driving mechanism includes a double-axis motor 9 installed on the right side of the filter tank body 1, and the right end output shaft of the double-axis motor 9 is fixedly connected to a rotating plate 10, and the eccentric part of the rotating plate 10 is rotatably connected to a connecting rod 11, and a second piston plate 38 that can slide up and down is arranged in the piston cylinder 12, and the upper end of the second piston plate 38 is rotatably connected to the other end of the connecting rod 11. In this way, when the rotating plate 10 rotates, the second piston plate 38 will reciprocate up and down through the connecting rod 11; As an embodiment of the present invention, it also includes a self-cleaning mechanism, which is used to comprehensively clean the sand and gravel. The self-cleaning mechanism includes a second bevel gear 26 installed on the rotating shaft 25. The left end output shaft of the dual-axis motor 9 extends to the inside of the filter tank body 1 and is installed with a first bevel gear 27. The first bevel gear 27 is meshed with the second bevel gear 26. A support mesh plate 18 is horizontally arranged at the inner bottom of the filter tank body 1. The support mesh plate 18 is fixedly connected to the inner wall of the filter tank body 1. The upper end of the support mesh plate 18 is symmetrically fixedly connected to two electric telescopic rods 19. The telescopic ends of the two electric telescopic rods 19 are commonly fixedly connected to a support tube 20. The upper end surface of the support tube 20 is higher than the conical tube 22. The upper end surface of the support tube 20 passes through the gap between the conical tube 22 and the inner wall of the filter tank body 1, and is slidably connected. A circular opening is opened at the inner bottom of the support tube 20. The rotating shaft 25 passes through the circular opening, and the inner bottom of the support cylinder 20 is symmetrically fixedly connected with two abutting hemispherical bodies 32. Four slide grooves 28 are evenly spaced on the inner side wall of the conical cylinder 22, and a slidable shaking plate 29 is arranged in each slide groove 28. Each shaking plate 29 is elastically connected to the inner wall of the slide groove 28 by a plurality of shaking springs 31 on one side away from the middle of the conical cylinder 22. In order to ensure the actual sealing, an elastic rubber skin can be arranged at the notch of each slide groove 28. A round head rod 30 is fixedly connected to the side of each shaking plate 29 away from the middle of the conical cylinder 22, and the other end of each round head rod 30 passes through the inner wall of the corresponding slide groove 28 and is slidably connected. The plurality of round head rods 30 cooperate with the two abutting hemispherical bodies 32. A placing plate 8 is fixedly connected to the right side of the filter tank body 1, and a sand and gravel discharge port 7 is arranged on the right side wall of the filter tank body 1. As an embodiment of the present invention, a wastewater outlet 15 is provided on the left inner wall of the filter tank body 1. Furthermore, a guide structure can be set on the left side of the wastewater outlet 15 to ensure that the subsequent water will fall directly into the separation tank 6 along the guide structure after being discharged. The guide structure can be a V-shaped guide plate or a guide tube body. A separation tank 6 is provided at the upper end of the water tank 4. The inner bottom of the separation tank 6 is connected to the inside of the water storage chamber 16 through multiple water openings 37. When used later, a layer of gauze can be placed on the inner bottom of the separation tank 6, and the gauze can be pressurized and limited by a ring body to facilitate subsequent cleaning operations. The water storage chamber 16 is filled with water, and a water collecting cover 35 is installed on the inner top of the water storage chamber 16. A liquid drop pipe 3 is installed on the inner bottom of the water collecting cover 35. 6. A normally closed solenoid valve is installed in the liquid downpipe 36, and a normally open solenoid valve is installed inside the liquid inlet pipe 2 and the liquid discharge pipe 17. A first liquid level sensor 21 is installed on the right inner wall of the filter tank body 1. The first liquid level sensor 21 is electrically connected to the dual-axis motor 9 and the two normally open solenoid valves. When the first liquid level sensor 21 senses the water body, it will control the dual-axis motor 9 and the two normally open solenoid valves to be energized for a period of time and closed. In addition, a second liquid level switch is also installed at the wastewater outlet 15. When the second liquid level switch senses the water body, the normally closed solenoid valve is controlled to be energized. Here, it is controlled by the PLC control program. The backwashing operation can be realized during the period of power-on. In addition, the dual-axis motor 9 can also be manually controlled separately to facilitate the subsequent sand and gravel discharge operation; As an embodiment of the present invention, a negative pressure cylinder 5 is fixedly connected to the left side of the water tank 4, a vent hole is opened on the left inner wall of the negative pressure cylinder 5, the right side of the negative pressure cylinder 5 is connected to the inside of the water storage chamber 16, and a first piston plate 33 that can slide left and right is arranged in the negative pressure cylinder 5. The left side of the first piston plate 33 is elastically connected to the left inner wall of the negative pressure cylinder 5 through a restoring spring 34. The restoring spring 34 here adopts a spring with a larger stiffness coefficient, which can achieve better effect in actual use.

[0023] In the present invention, during normal use, the water to be filtered is discharged from the liquid inlet pipe 2, falls into the conical cylinder 22, and then passes through the sand and gravel, and is discharged from the filter round mouth 23, and finally falls to the inner bottom of the filter tank body 1, and then is discharged to the outside from the drain pipe 17; When the sand and gravel filter out more impurities and the water permeability is poor, the water will slowly gather. When the water level reaches the first liquid level sensor 21, the dual-axis motor 9, the normally closed solenoid valve and the two normally open solenoid valves are energized for a period of time and closed. After the two normally open solenoid valves are energized, the liquid inlet pipe 2 and the liquid discharge pipe 17 are sealed. After the dual-axis motor 9 is started, it will drive the rotating plate 10 to rotate, so that the second piston plate 38 can be reciprocated up and down by using the connecting rod 11. After the second piston plate 38 reciprocates up and down, the first one-way tube 13 and the second one-way tube 14 and the internal one-way valve will be used to draw the water in the water tank 4 into the , and then injected into the inner bottom space of the filter tank body 1. As the water body is continuously injected, the bottom space of the filter tank body 1 will be filled with water first, and then as the water body continues to increase, it will pass through the sand and gravel and converge with the water body above the sand and gravel. As the water body continues to increase, the overall water level will move up. When the water level moves up to the wastewater discharge port 15, the water body will fall into the separation tank 6, which will continuously generate liquid flow in the bottom space of the filter tank body 1, the sand and gravel layer, the top space of the filter tank body 1 and the wastewater discharge port 15. The liquid flow can take away impurities on the surface of the sand and gravel layer and discharge them from the wastewater discharge port 15; When the inner bottom space of the piston cylinder 12 is pumped, after the water in the water storage chamber 16 is pumped away, the overall space increases and the air pressure decreases, causing the first piston plate 33 to move rightward and restore the spring 34. When the wastewater is discharged at the wastewater outlet 15 and the discharged water falls into the separation tank 6, the normally closed solenoid valve is energized to connect the liquid drop pipe 36. At this time, due to the negative pressure, the water in the separation tank 6 will be pumped into the water storage chamber 16 (at the same time, the first piston plate 33 will move leftward under the elastic action of the restoration spring 34). In this way, the impurities in the water can be quickly separated by using the negative pressure in combination with the gauze. In the above process, after the dual-axis motor 9 is started, the first bevel gear 27 and the second bevel gear 26 will drive the shaft 25 to rotate. The rotation of the shaft 25 can drive the cone-shaped cylinder 22 to rotate. After the cone-shaped cylinder 22 rotates, centrifugal force will be generated. The centrifugal force generated will make the sand and gravel slide upward along the side wall of the cone-shaped cylinder 22. At the same time, the rotation of the cone-shaped cylinder 22 will also rotate the round head rod 30. During the rotation, it will intermittently contact the moving hemisphere 32, and the two moving hemispheres 32 that are moved at the same time are symmetrical. In this way, after the rotation, when the moving hemisphere 32 is moved, it will push The corresponding shaking plate 29 slides along the slide groove 28, and when it leaves the abutting hemisphere 32, it moves back under the elastic action of the shaking spring 31, so that the multiple shaking plates 29 will shake continuously and symmetrically. When the two symmetrical shaking plates 29 shake at the same time, the abutting hemisphere 32 will be thrown to the middle, and the sand and gravel will collide in the middle and finally fall to the inner bottom of the conical tube 22, and so on. During the collision of the sand and gravel, impurities tightly adhered to the surface can fall off, and the gap between the overall sand and gravel becomes larger in this process, so that the impurities mixed in the sand and gravel can also be taken away by the water flow, so that the overall cleaning effect is excellent; In addition, by adopting the above method, after a single backwash is completed, the sand and gravel will be redistributed, so that the service life of the whole sand and gravel will be consumed evenly, avoiding the situation that the service life of the top layer of sand and gravel is low and the service life of the bottom layer of sand and gravel is high (after long-term use of sand and gravel, the water may contain microorganisms, such as bacteria, algae, etc. These microorganisms may reproduce in the sand and gravel layer to form biofilms or biological communities, further aggravating the blockage of the filter medium, and certain chemicals in the water may react with the sand and gravel, causing changes in the surface properties of the sand and gravel or structural damage, thereby affecting its filtration performance and service life); After backwashing is completed, the impurities in the separation tank 6 can be removed regularly and the gauze can be replaced; When the overall sand and gravel have reached the end of their service life, the electric telescopic rod 19 can be started to retract, allowing the support tube 20 to move downward until its upper end surface is flush with the upper end surface of the conical tube 22, and the sand and gravel discharge port 7 is fully opened. After the staff places a collection box that fits the side wall of the filter tank body 1 on the placement plate 8, they can start the dual-axis motor 9 alone. At this time, as the support tube 20 moves downward and drives the two moving hemispheres 32 to move downward, the round head rod 30 rotates and no longer contacts the moving hemispheres 32. At this time, the conical tube 22 will, under the action of centrifugal force, allow the internal sand and gravel to be discharged from the sand and gravel discharge port 7, thereby realizing the sand and gravel discharge operation. After the sand and gravel are discharged, an appropriate amount of new sand and gravel can be added from the sand and gravel adding port 3.

[0024] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A shallow sand filter with protective function, characterized in that: include: A filter tank body (1), wherein a liquid inlet pipe (2) is installed at the inner top of the filter tank body (1), and a liquid discharge pipe (17) is installed at the inner bottom of the filter tank body (1); A gravel filter mechanism, the gravel filter mechanism is used to filter water, the gravel filter mechanism comprises a horizontal plate (24) fixedly connected between the front and rear inner walls of the bottom part of the filter tank body (1), the upper end of the horizontal plate (24) is rotatably connected to a rotating shaft (25), the upper end of the rotating shaft (25) is fixedly connected to a conical cylinder (22), the conical cylinder (22) is filled with gravel, the upper end surface of the gravel is lower than the middle part of the conical cylinder (22), and the inner bottom of the conical cylinder (22) is provided with a plurality of filtering circular openings (23); A backwashing mechanism, the backwashing mechanism comprising a water tank (4) fixedly connected to the left side of the filter tank body (1), a water storage chamber (16) being arranged inside the water tank (4), a piston cylinder (12) being fixedly connected to the right side of the filter tank body (1), the inner bottom of the piston cylinder (12) being connected to the inner bottom space of the water storage chamber (16) via a first one-way tube (13), the inner bottom space of the piston cylinder (12) being connected to a second one-way tube (14), and the second one-way tube (14) being connected to the inner bottom space of the filter tank body (1); A driving mechanism, wherein the driving mechanism is used to drive the backwashing mechanism to operate; The self-cleaning mechanism is used for comprehensively cleaning the sand and gravel.

2. A shallow sand filter with protective function according to claim 1, characterized in that: The driving mechanism comprises a double-shaft motor (9) mounted on the right side of the filter tank body (1); the right end output shaft of the double-shaft motor (9) is fixedly connected to a rotating plate (10); the eccentric portion of the rotating plate (10) is rotatably connected to a connecting rod (11); a second piston plate (38) that can slide up and down is arranged in the piston cylinder (12); the upper end of the second piston plate (38) is rotatably connected to the other end of the connecting rod (11).

3. A shallow sand filter with protective function according to claim 1, characterized in that: One-way valves are installed inside the first one-way tube (13) and the second one-way tube (14). The one-way valve inside the first one-way tube (13) allows the flow of water from the water storage chamber (16) to the bottom space inside the piston cylinder (12) in one direction, while the one-way valve inside the second one-way tube (14) allows the flow of water from the bottom space inside the piston cylinder (12) to the bottom inside the filter tank body (1).

4. A shallow sand filter with protective function according to claim 2, characterized in that: The self-cleaning mechanism comprises a second bevel gear (26) mounted on a rotating shaft (25); the left end output shaft of the dual-shaft motor (9) extends into the interior of the filter tank body (1) and is mounted with a first bevel gear (27); the first bevel gear (27) is meshed with the second bevel gear (26).

5. A shallow sand filter with protective function according to claim 4, characterized in that: A support mesh plate (18) is horizontally arranged at the inner bottom of the filter tank body (1), and the support mesh plate (18) is fixedly connected to the inner wall of the filter tank body (1). Two electric telescopic rods (19) are symmetrically fixedly connected to the upper end of the support mesh plate (18), and the telescopic ends of the two electric telescopic rods (19) are commonly fixedly connected to a support cylinder (20), the upper end surface of the support cylinder (20) is higher than the conical cylinder (22), the upper end surface of the support cylinder (20) passes through the gap between the conical cylinder (22) and the inner wall of the filter tank body (1), and is slidably connected, the inner bottom of the support cylinder (20) is provided with a circular opening, the rotating shaft (25) passes through the circular opening, and the inner bottom of the support cylinder (20) is Two abutting hemispherical bodies (32) are symmetrically and fixedly connected to the inner wall of the conical cylinder (22), four sliding grooves (28) are evenly spaced on the inner wall of the conical cylinder (22), and a slidable shaking plate (29) is arranged in each of the sliding grooves (28). The side of each shaking plate (29) away from the middle of the conical cylinder (22) is elastically connected to the inner wall of the sliding groove (28) through a plurality of shaking springs (31), and the side of each shaking plate (29) away from the middle of the conical cylinder (22) is fixedly connected to a round head rod (30), and the other end of each round head rod (30) penetrates the inner wall of the corresponding sliding groove (28) and is slidably connected, and the plurality of round head rods (30) cooperate with the two abutting hemispherical bodies (32).

6. A shallow sand filter with protective function according to claim 2, characterized in that: A wastewater discharge port (15) is provided on the left inner wall of the filter tank body (1), a separation tank (6) is provided at the upper end of the water tank (4), the inner bottom of the separation tank (6) is connected to the inside of the water storage chamber (16) through a plurality of water through-holes (37), the water storage chamber (16) is filled with water, a water collecting cover (35) is installed on the inner top of the water storage chamber (16), and a liquid drop pipe (36) is installed on the inner bottom of the water collecting cover (35).

7. A shallow sand filter with protective function according to claim 6, characterized in that: A normally closed electromagnetic valve is installed in the liquid drop pipe (36), and a normally open electromagnetic valve is installed in the liquid inlet pipe (2) and the liquid discharge pipe (17). A first liquid level sensor (21) is installed on the right inner wall of the filter tank body (1), and the first liquid level sensor (21) is electrically connected to the dual-axis motor (9) and the two normally open electromagnetic valves.

8. A shallow sand filter with protective function according to claim 7, characterized in that: A negative pressure cylinder (5) is fixedly connected to the left side of the water tank (4), a vent hole is provided on the left inner wall of the negative pressure cylinder (5), the right side of the negative pressure cylinder (5) is connected to the inside of the water storage chamber (16), and a first piston plate (33) that can slide left and right is provided in the negative pressure cylinder (5), and the left side of the first piston plate (33) is elastically connected to the left inner wall of the negative pressure cylinder (5) via a restoring spring (34).

9. A shallow sand filter with protective function according to claim 1, characterized in that: A placement plate (8) is fixedly connected to the right side of the filter tank body (1), and a sand and gravel discharge port (7) is provided on the right side wall of the filter tank body (1).

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