CN211423473U

CN211423473U - Backflow preventer device capable of adjusting seat positive pressure difference and flow resistance

Info

Publication number: CN211423473U
Application number: CN201922301549.5U
Authority: CN
Inventors: 陈庆平
Original assignee: Fujian Quanpai Valve Technology Co ltd
Current assignee: Fujian Quanpai Valve Technology Co ltd
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2020-09-04
Anticipated expiration: 2029-12-20

Abstract

The utility model relates to a backflow preventer device capable of adjusting positive pressure difference and flow resistance of a return seat, which comprises a main valve body, wherein the main valve body is provided with a water inlet, a middle cavity and a water outlet which are communicated with each other in sequence from front to back along the axial direction of the main valve body; the front end of the connecting rod is screwed with a water inlet valve clack which is used for axially sliding on a water inlet guide sleeve in the guide cylinder to open and close a water inlet, the rear side of the water inlet valve clack is provided with a spring seat which is coaxially and fixedly connected on the connecting rod, and a main spring is arranged between the spring seat and the rear inner end surface of the guide cylinder; the rear end of the connecting rod is connected with a water outlet valve clack which is used for axially sliding on a water outlet guide sleeve coaxially arranged in the water outlet to open and close an opening at the rear end of the guide cylinder, and the structure is simple.

Description

Backflow preventer device capable of adjusting seat positive pressure difference and flow resistance

Technical Field

The utility model relates to a backflow preventer device capable of adjusting the positive pressure difference and the flow resistance of a seat.

Background

With the rapid development of urban construction and the improvement of the living standard of people, the requirements of people on the quality of tap water are continuously improved, and the attention on the health of drinking water is more and more urgent. In recent years, water backflow pollution events are continuously generated in some places of China. In the water supply pipeline, the backflow preventer is used as an effective facility for preventing backflow pollution of tap water and ensuring water quality safety of water supply. Aiming at the water supply condition in China, national standards and industrial standards all require to mount a backflow preventer forcibly, and the requirements of the backflow preventer on the setting occasion, safety and resistance performance are stipulated.

The backflow preventer is a hydraulic control combination valve which strictly limits the unidirectional flow of pressure water in a pipeline and has the function of preventing medium in the pipeline from flowing from the outlet end to the inlet end of the device under any working condition. The key technology is that the traditional blocking and intercepting method is abandoned, and the water which flows backwards or flows back in a critical way is drained out of the valve by adopting a guiding method through the drainer and adopting a guiding method. The maximum functional effect is to prevent the pollution caused by the backflow of the medium and ensure the water supply safety.

Compared with the foreign countries, the water supply pressure in China is lower. The domestic water supply pressure is 0.25-0.3 MPa, and the domestic water supply pressure is doubled compared with the domestic water supply pressure, so that the water supply cost is increased greatly if the water supply pressure of the urban pipe network is integrally increased. At present, the products at home and abroad ensure the safety, and meanwhile, the problems of large head loss and the like generally exist, if the head loss of the pressure-reducing backflow preventer reaches 7-10 m water columns (namely 0.07-0.10 MPa), the backflow preventer with the pressure loss of more than 30 percent is installed on the domestic water supply pipeline, a plurality of pipelines with low water supply pressure cannot normally supply water, the head loss of some backflow preventer products is reduced, and the safety of product pipeline partition is also reduced. Can not meet the national and industrial standards or design specifications and actual use requirements. The existing backflow preventer cannot give consideration to both the safety performance and the resistance performance of the partition.

SUMMERY OF THE UTILITY MODEL

In view of the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a backflow preventer device capable of adjusting the seat positive pressure difference and the flow resistance.

In order to solve the technical problem, the technical scheme of the utility model is that: a backflow preventer device capable of adjusting positive pressure difference and flow resistance of a return seat comprises a main valve body, wherein the main valve body is sequentially provided with a water inlet, an intermediate cavity and a water outlet which are communicated from front to back along the axial direction of the main valve body;

a guide cylinder with openings at two ends is coaxially and fixedly arranged on the middle cavity, an annular gap is formed between the periphery of the guide cylinder and the middle cavity, and a connecting rod coaxially penetrates through the middle of the opening at the rear end of the guide cylinder;

the front end of the connecting rod is screwed with a water inlet valve clack which is used for axially sliding on a water inlet guide sleeve in the guide cylinder to open and close a water inlet, the rear side of the water inlet valve clack is provided with a spring seat which is coaxially and fixedly connected on the connecting rod, and a main spring is arranged between the spring seat and the rear inner end surface of the guide cylinder;

the rear end of the connecting rod is connected with a water outlet valve clack which is used for axially sliding on a water outlet guide sleeve coaxially arranged in the water outlet to open and close an opening at the rear end of the guide cylinder;

the water inlet valve clack and the water outlet valve clack are composed of a front thin section and a rear thick section, the front thin section and the rear thick section are connected through a cone chamfer, O-shaped sealing rings are arranged between the water inlet valve clack and the water inlet guide sleeve and between the water outlet valve clack and the water outlet guide sleeve, and the O-shaped sealing rings are in interference fit with the rear thick section during non-return drainage and in clearance fit with the front thin section during normal water supply.

Preferably, the annular gap is fixedly provided with a radiation rib used for connecting the periphery of the guide cylinder in the radial direction, the radiation rib does not close the through-flow section of the annular gap, the front end opening of the guide cylinder is larger than the rear end opening, and the water inlet guide sleeve is coaxially arranged in the guide cylinder from the front end opening.

Preferably, a water inlet valve seat used for being in sealing fit with the water inlet valve clack is coaxially arranged on the water inlet, and a water outlet valve seat used for being in sealing fit with the water outlet valve clack is coaxially arranged on the opening at the rear end of the guide cylinder.

Preferably, the middle part of the water inlet valve seat is connected with a guide pin with a rear convex conical surface through a radiation rib, and the middle part of the water inlet valve clack is screwed with a guide nut with a front concave conical surface; the radial radiating rib does not close the through-flow section of the water inlet valve seat.

Preferably, a guide sleeve is coaxially and fixedly arranged in the middle of the opening at the rear end of the guide cylinder through a radial radiation rib, the connecting rod coaxially penetrates through the guide sleeve, a limiting boss for abutting against the front end face of the guide sleeve to carry out backward movement limiting is coaxially and fixedly arranged on the rod body of the connecting rod, and the through-flow section of the opening at the rear end of the guide cylinder is not sealed by the radiation rib.

Preferably, the rear end of the connecting rod is coaxially and fixedly provided with a thin section external thread, a limit step is arranged between the external thread and the rod body of the connecting rod, the middle part of the water outlet valve clack is coaxially and fixedly provided with a sliding sleeve through a radial radiation rib, the sliding sleeve is coaxially arranged on the external thread in a penetrating way, the front end of the sliding sleeve is abutted with the limit step, the rear end of the sliding sleeve is abutted with an auxiliary spring adjusting bolt screwed on the external thread through an auxiliary spring and a thread, and the radiation rib does not seal the through-flow section of the water outlet valve cla.

Preferably, the outer side of the main valve body is provided with a drainer, the middle cavity is communicated with a drainage water inlet of the drainer, the water inlet is communicated with a front end water inlet of the drainer, and the water outlet is communicated with a rear end water inlet of the drainer.

Preferably, the drainer includes the valve body, be equipped with drainage water inlet and drainage delivery port on the valve body, be equipped with the dull and stereotyped sealed valve clack that alternates and carry out the reciprocal translation on the valve body between drainage water inlet and the drainage delivery port, the front end of dull and stereotyped sealed valve clack links firmly the preceding piston that is located the valve body preceding pressure chamber, the rear end links firmly the back piston that is located the valve body back pressure chamber, non-tip is equipped with the through-hole of translation switch-on drainage water inlet and drainage delivery port, be equipped with the front end water inlet on the preceding pressure chamber, be equipped with the rear end water inlet on the back pressure.

Preferably, the water drainage inlet and the water drainage outlet are positioned on the valve body between the front pressure cavity and the rear pressure cavity, and the valve body is provided with a straight sliding channel for the plate sealing valve clack to move back and forth in a reciprocating manner; an annular sealing valve seat, an O-shaped ring, an adjusting ring and a water inlet external thread joint are sequentially arranged inside the drainage water inlet from inside to outside, an annular sealing valve seat, an O-shaped ring and an adjusting ring are sequentially arranged inside the drainage water outlet from inside to outside, the adjusting ring and the water inlet external thread joint are screwed on the valve body, the sealing valve seat in the drainage water inlet is contacted with the upper surface of the flat sealing valve clack, and the sealing valve seat in the drainage water outlet is contacted with the lower surface of the flat sealing valve clack; the front end of the front pressure cavity is screwed with a front cover, and the rear end of the rear pressure cavity is screwed with a rear cover; the spring is positioned on the front pressure cavity, the axial direction of the spring is the translation direction of the flat plate sealing valve clack, the rear end of the spring is abutted with the front piston, and the front end of the spring is abutted on the front cover; the front cover is screwed with an adjusting screw, the adjusting screw is coaxial with the spring, the inner end of the adjusting screw is fixedly provided with a mounting plate positioned on the front pressure cavity, and the front end of the spring is propped against the mounting plate.

Compared with the prior art, the utility model discloses following beneficial effect has: the backflow preventer device capable of adjusting the seat positive pressure difference and the flow resistance is simple in structure, the seat positive pressure difference and the flow resistance of the backflow preventer can be adjusted, the backflow preventer can be adjusted to a safe value, and the flow resistance head loss is adjusted to the minimum under the condition that the pipeline is guaranteed to be cut off in safety. The backflow preventer not only ensures the safety of pipeline partition, but also has lower head loss, achieves the standard requirements, solves the big problem that the safety performance and the resistance performance of the partition of the common backflow preventer can not be simultaneously considered, and meets the use requirements of fields needing to prevent water backflow pollution of water supply pipe networks in various buildings, fire fighting, industrial and mining, gardens, water treatment and other systems in China.

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

Drawings

Fig. 1 is a schematic view of the non-return drainage state of the embodiment of the present invention.

Fig. 2 is a partially enlarged view a of fig. 1.

Fig. 3 is a partially enlarged view B of fig. 1.

Fig. 4 is a schematic view of the normal water supply state of the embodiment of the present invention.

Fig. 5 is a partial enlarged view of C of fig. 4.

Fig. 6 is a partial enlarged view D of fig. 4.

Fig. 7 is a state view of the drainer of fig. 1.

Fig. 8 is a state diagram of the drainer of fig. 4.

Detailed Description

In order to make the aforementioned and other features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

As shown in fig. 1 to 8, a backflow preventer device capable of adjusting positive pressure difference and flow resistance of a return seat comprises a main valve body 22, wherein the main valve body is sequentially provided with a water inlet 23, an intermediate cavity 24 and a water outlet 25 which are communicated with each other from front to back along the axial direction of the main valve body;

a guide cylinder 26 with openings at two ends is coaxially and fixedly arranged on the middle cavity, an annular gap is formed between the periphery of the guide cylinder and the middle cavity, and a connecting rod 27 is coaxially arranged in the middle of the opening at the rear end of the guide cylinder in a penetrating manner;

the front end of the connecting rod is screwed with a water inlet valve flap 29 which is used for axially sliding on a water inlet guide sleeve 28 in the guide cylinder to open and close the water inlet, the rear side of the water inlet valve flap is provided with a spring seat 30 which is coaxially and fixedly connected on the connecting rod, and a main spring 31 is arranged between the spring seat and the rear inner end surface of the guide cylinder;

the rear end of the connecting rod is connected with a water outlet valve flap 33 which is used for axially sliding on a water outlet guide sleeve 32 coaxially arranged in the water outlet to open and close the rear end opening of the guide cylinder;

the water inlet valve clack and the water outlet valve clack are composed of a front thin section 34 and a rear thick section 35, the front thin section is connected with the rear thick section through a cone chamfer 36, O-shaped sealing rings 37 are arranged between the water inlet valve clack and the water inlet guide sleeve and between the water outlet valve clack and the water outlet guide sleeve, and are in interference fit with the rear thick section during non-return drainage of the O-shaped sealing rings and in clearance fit with the front thin section during normal water supply.

In the embodiment of the present invention, the radial rib 38 for connecting the periphery of the guide cylinder is fixedly arranged on the annular gap, the radial rib does not close the through-flow cross section of the annular gap, the front opening of the guide cylinder is larger than the rear opening, and the water inlet guide sleeve is coaxially arranged inside the guide cylinder from the front opening.

The embodiment of the utility model provides an in, the coaxial intake valve seat 39 that is used for sealing the complex with the water inlet valve clack that is equipped with on the water inlet, the coaxial play water valve seat 40 that is used for sealing the complex with the play water valve clack that is equipped with on the guide cylinder rear end opening.

In the embodiment of the utility model, the middle part of the water inlet valve seat is connected with a guide pin 41 with a rear convex conical surface through a radiation rib, and the middle part of the water inlet valve clack is screwed with a guide nut 42 with a front concave conical surface; the radial radiating rib does not close the through-flow section of the water inlet valve seat.

The embodiment of the utility model provides an in, guide cylinder rear end opening middle part is through radial radiation muscle coaxial set firmly a guide pin bushing 43, and the connecting rod is coaxial to be worn to establish on the guide pin bushing, and the pole body of connecting rod is coaxial set firmly to be used for the top to connect guide pin bushing preceding terminal surface to carry out the spacing boss 44 that moves back, and radiation muscle does not seal guide cylinder rear end open-ended through-flow cross-section.

The embodiment of the utility model provides an in, the rear end of connecting rod is coaxial to be set firmly thin section external screw thread 45, spacing step 46 has between the pole body of external screw thread and connecting rod, the middle part of going out the water valve clack has set firmly a sliding sleeve 47 through radial radiation muscle is coaxial, on the external screw thread was worn to locate by the sliding sleeve, the sliding sleeve front end was butted mutually with spacing step, the sliding sleeve rear end was butted mutually through auxiliary spring 48 and auxiliary spring adjusting bolt 49 that the screw thread connects on the external screw thread soon, the through-flow cross-section of water valve clack is not sealed to the radiation muscle.

The embodiment of the utility model provides an in, the outer side of the main valve body is equipped with drainer 50, and the drainage water inlet intercommunication of middle chamber and drainer, water inlet and the front end water inlet intercommunication of drainer, the rear end water inlet intercommunication of delivery port and drainer.

The embodiment of the utility model provides an in, the drainer includes valve body 1, be equipped with drainage water inlet 2 and drainage delivery port 3 on the valve body, be equipped with the dull and stereotyped sealed valve clack 4 of alternate translation that reciprocates on the valve body between drainage water inlet and the drainage delivery port, the front end of dull and stereotyped sealed valve clack links firmly preceding piston 6 that is located on the preceding pressure chamber 5 of valve body, the rear end links firmly the back piston 8 that is located on the valve body back pressure chamber 7, non-tip is equipped with the through-hole 9 of translation switch-on drainage water inlet and drainage delivery port, be equipped with front end water inlet 10 on the preceding pressure chamber, be equipped with rear end water inlet 11 on the back pressure. The through holes for horizontally communicating the drainage water inlet and the drainage water outlet have different communication calibers with the drainage water inlet and the drainage water outlet along with the change of the front end pressure and the rear end pressure, and the drainage quantity is different.

The embodiment of the utility model provides an in, drainage water inlet and drainage delivery port are located the valve body between preceding pressure chamber and the back pressure chamber, offer the straight chute way 13 that is used for the reciprocal front and back translation of dull and stereotyped seal valve clack on the valve body, and the flow resistance coefficient is low, and loss of pressure is little. Inside by interior and outer annular sealed disk seat 14 that is equipped with in proper order of drainage water inlet, O type circle 15, adjusting ring 16, water inlet external thread joint 17, inside by interior and outer annular sealed disk seat that is equipped with in proper order of drainage delivery port, O type circle, adjusting ring, wherein the adjusting ring, the equal screw thread of water inlet external thread joint connects soon on the valve body, can connect external thread joint on the drainage delivery port, sealed disk seat and the contact of dull and stereotyped sealed valve clack upper surface in the drainage delivery port, sealed disk seat and the contact of dull and stereotyped sealed valve clack lower surface in the drainage delivery port, the leakproofness is good. The front end of the front pressure cavity is screwed with a front cover 19, and the rear end of the rear pressure cavity is screwed with a rear cover 20. The spring is positioned on the front pressure cavity, the axial direction of the spring is the translation direction of the flat plate sealing valve clack, the rear end of the spring is abutted with the front piston, and the front end of the spring is abutted on the front cover. The front cover is screwed with an adjusting screw 21, the adjusting screw is coaxial with the spring, the inner end of the adjusting screw is fixedly provided with a mounting plate 18 positioned on the front pressure cavity, and the front end of the spring is propped against the mounting plate. When the adjusting screw is rotated, the compression degree of the spring can be adjusted, so that the flow and the opening and closing pressure of the drainer can be further adjusted, and the drainer can be closed by adjusting the adjusting screw as required.

The working method of the backflow preventer device capable of adjusting the seat positive pressure difference and the flow resistance comprises the following steps of: (1) during adjustment, the front end of the connecting rod is screwed with the water inlet valve clack in a threaded manner, so that the axial position of the water inlet valve clack is changed by rotating the connecting rod to change the screwing degree, and when the distance between the water inlet valve clack and the spring seat is changed, the pre-tightening force for resetting the main spring is changed; the axial position of the auxiliary spring is changed by rotating the auxiliary spring adjusting bolt, and the pre-tightening force of the auxiliary spring is changed to ensure necessary sealing specific pressure; (2) as shown in fig. 4, when the pressure of the water inlet is greater than the pressure of the middle cavity and the pressure of the middle cavity is greater than the pressure of the water outlet, the pressure difference pushes the water inlet valve flap to leave the water inlet valve seat, the water inlet valve flap pushes the connecting rod, the connecting rod pushes the water outlet valve flap to be fully opened, the main spring is compressed to the limiting position of the connecting rod, the drainer is closed, and the backflow preventer is in a normal water supply state; due to the guiding effect of the cone chamfer angle, a certain gap is formed between the water inlet valve clack and the water outlet guide sleeve and between the water inlet valve clack and the water outlet guide sleeve, so that an O-shaped sealing ring on the water inlet valve clack is separated from the water inlet guide sleeve and an O-shaped sealing ring on the water outlet valve clack is separated from the water outlet guide sleeve, the flow resistance of the O-shaped sealing ring is eliminated, the flow resistance of the backflow preventer is reduced, and the head loss is reduced; (3) as shown in fig. 1, when the pressure of the water outlet is greater than the pressure of the middle cavity, and the pressure of the middle cavity is greater than the pressure of the water inlet, and when the two-stage check valve is closed, the water inlet valve flap and the water inlet guide sleeve, and the water outlet valve flap and the water outlet guide sleeve are provided with the O-shaped sealing ring sealing structures, so that the water inlet valve flap and the water outlet valve flap are matched with the water inlet guide sleeve and the water outlet guide sleeve to form the cylindrical O-shaped sealing ring seal, the water inlet valve flap and the water outlet valve flap are pushed to the water inlet valve seat and the water outlet valve; meanwhile, a guide nut with a front concave conical surface is matched with a guide pin with a rear convex conical surface, so that the valve clack is matched with the valve seat to be in a concentric position; the double action of water power and main spring force forms effective non-return sealing, and the drainer is opened to drain the water flowing backwards instantly out of the valve.

The embodiment of the utility model provides an in step (2), (3), the drainer is installed in the outside of backflow preventer main valve body, and the drainage water inlet communicates with each other with the middle chamber, and the drainage delivery port communicates with each other with the atmosphere, and the water inlet of backflow preventer main valve body is connected to the front end water inlet, and the delivery port of backflow preventer main valve body is linked to the rear end water inlet, relies on the change of both sides pressure to control opening and close of drainer. When the front end pressure P1 is greater than the rear end pressure P2, the pressure difference pushes the front piston, the flat plate sealing valve clack and the rear piston to move backwards to limit, the flat plate sealing valve clack completely covers a channel between the drainage water inlet and the drainage water outlet, and the drainer is closed; when the rear end pressure P2 is greater than the front end pressure P1, the pressure difference pushes the rear piston, the flat plate sealing valve clack and the front piston to move forwards to limit, the through hole in the flat plate sealing valve clack is communicated with the channel between the drainage water inlet and the drainage water outlet, and the drainer drains water. The water in the middle cavity can be discharged smoothly after the non-return device of the backflow preventer is sealed, and the water outside can be prevented from flowing backwards into the main valve body, so that the backflow preventer is safe and reliable.

The present invention is not limited to the above preferred embodiment, and any person can obtain other various forms of backflow preventer devices capable of adjusting the positive pressure difference and the flow resistance of the seat. All the equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the present invention.

Claims

1. The utility model provides an adjustable backflow preventer device that seat positive pressure differential and flow resistance return, includes the main valve body, the main valve body is equipped with water inlet, middle chamber, the delivery port that is linked together, its characterized in that from the front to the back in proper order along its axial:

2. A backflow preventer device according to claim 1, which is capable of adjusting back to a positive pressure differential and flow resistance, wherein: the annular gap is radially and fixedly provided with a radiation rib used for connecting the periphery of the guide cylinder, the radiation rib does not close the through-flow section of the annular gap, the front end opening of the guide cylinder is larger than the rear end opening, and the water inlet guide sleeve is coaxially arranged in the guide cylinder from the front end opening.

3. A backflow preventer device according to claim 1, which is capable of adjusting back to a positive pressure differential and flow resistance, wherein: the water inlet is coaxially provided with a water inlet valve seat which is in sealing fit with the water inlet valve clack, and the rear end opening of the guide cylinder is coaxially provided with a water outlet valve seat which is in sealing fit with the water outlet valve clack.

4. A backflow preventer device according to claim 3, which is capable of adjusting back to a positive pressure differential and flow resistance, wherein: the middle part of the water inlet valve seat is connected with a guide pin with a rear convex conical surface through a radiation rib, and the middle part of the water inlet valve clack is screwed with a guide nut with a front concave conical surface; the radial radiating rib does not close the through-flow section of the water inlet valve seat.

5. A backflow preventer device according to claim 1, which is capable of adjusting back to a positive pressure differential and flow resistance, wherein: the middle part of the opening at the rear end of the guide cylinder is coaxially and fixedly provided with a guide sleeve through a radial radiation rib, the connecting rod coaxially penetrates through the guide sleeve, a rod body of the connecting rod is coaxially and fixedly provided with a limiting boss for jacking the front end surface of the guide sleeve to carry out backward movement limiting, and the radiation rib does not seal the through-flow section of the opening at the rear end of the guide cylinder.

6. A backflow preventer device according to claim 1, which is capable of adjusting back to a positive pressure differential and flow resistance, wherein: the rear end of connecting rod is coaxial to have set firmly the thin section external screw thread, has spacing step between the body of external screw thread and connecting rod, and the middle part of going out the water valve clack has set firmly a sliding sleeve through radial radiation muscle is coaxial, and the sliding sleeve is coaxial to be worn to locate on the external screw thread, and the sliding sleeve front end is butted mutually with spacing step, and the sliding sleeve rear end is butted mutually through auxiliary spring adjusting bolt that auxiliary spring and screw thread connect on the external screw thread soon, and the through-flow cross-section of water valve clack is not sealed to the radiation muscle.

7. A backflow preventer device according to claim 1, which is capable of adjusting back to a positive pressure differential and flow resistance, wherein: the outer side of the main valve body is provided with a drainer, the middle cavity is communicated with a drainage water inlet of the drainer, the water inlet is communicated with a front water inlet of the drainer, and the water outlet is communicated with a rear water inlet of the drainer.

8. A backflow preventer device according to claim 7, which is capable of adjusting back to a positive pressure differential and flow resistance, wherein: the drainer comprises a valve body, a drainage water inlet and a drainage water outlet are arranged on the valve body, a flat sealing valve clack which is inserted into the valve body to perform reciprocating translation is arranged between the drainage water inlet and the drainage water outlet, a front piston which is positioned on a front pressure cavity of the valve body is fixedly connected to the front end of the flat sealing valve clack, a rear piston which is positioned on a rear pressure cavity of the valve body is fixedly connected to the rear end of the flat sealing valve clack, a through hole which is used for horizontally moving and connecting the drainage water inlet and the drainage water outlet is formed in a non-end part of the flat sealing valve clack.

9. A backflow preventer device according to claim 8, which is capable of adjusting back to a positive pressure differential and flow resistance, wherein: the water discharging water inlet and the water discharging water outlet are positioned on the valve body between the front pressure cavity and the rear pressure cavity, and the valve body is provided with a straight sliding channel for the plate sealing valve clack to move back and forth in a reciprocating manner; an annular sealing valve seat, an O-shaped ring, an adjusting ring and a water inlet external thread joint are sequentially arranged inside the drainage water inlet from inside to outside, an annular sealing valve seat, an O-shaped ring and an adjusting ring are sequentially arranged inside the drainage water outlet from inside to outside, the adjusting ring and the water inlet external thread joint are screwed on the valve body, the sealing valve seat in the drainage water inlet is contacted with the upper surface of the flat sealing valve clack, and the sealing valve seat in the drainage water outlet is contacted with the lower surface of the flat sealing valve clack; the front end of the front pressure cavity is screwed with a front cover, and the rear end of the rear pressure cavity is screwed with a rear cover; the spring is positioned on the front pressure cavity, the axial direction of the spring is the translation direction of the flat plate sealing valve clack, the rear end of the spring is abutted with the front piston, and the front end of the spring is abutted on the front cover; the front cover is screwed with an adjusting screw, the adjusting screw is coaxial with the spring, the inner end of the adjusting screw is fixedly provided with a mounting plate positioned on the front pressure cavity, and the front end of the spring is propped against the mounting plate.