A backflow prevention check valve

Abstract

This utility model provides an anti-backflow check valve, belonging to the field of mechanical technology. It solves the problem of inconvenient assembly. It includes a valve body with a water outlet at the front end and an annular positioning seat at the rear end, a valve seat threaded to the rear end of the valve body, and a guide cylinder fixed inside the valve body. A pressure relief port is provided on the side of the valve body. The valve body contains a first check valve assembly and a diaphragm whose front end abuts against the rear end of the guide cylinder. The first check valve assembly includes a first check spring, a first core rod passing through the diaphragm, and a first sealing plate fixed to the front end of the first core rod. The rear edge of the diaphragm abuts against the positioning seat. A water-passing plate is provided inside the valve body and fixedly connected to the rear end of the diaphragm. The front end of the valve seat abuts against the rear side of the water-passing plate. The water-passing plate has a central through hole and several water passage holes. The first core rod passes through the central through hole, and the first check spring is sleeved on the first core rod, with its two ends abutting against the rear ends of the water-passing plate and the first core rod, respectively. It has advantages such as convenient assembly.

Description

Technical Field

[0001] This utility model belongs to the field of mechanical technology and relates to an anti-backflow check valve. Background Technology

[0002] A check valve is a valve specifically designed to prevent backflow of fluid. For example, a two-stage check valve disclosed in patent application number 201020266891.2 includes a valve body and a valve core. The valve body has a valve seat, and the valve core is movably disposed within the valve body. The valve seat has an inlet and an outlet located at opposite ends. The valve core includes a primary valve core at the inlet and a secondary valve core at the outlet. The valve body has an vent. The primary valve core includes a valve stem, a diaphragm, a gasket, and a spring. The valve stem is generally cylindrical and has a boss at its front end. A gasket is located at the rear end of the valve stem. A valve cover is threaded to the front end of the valve body. The valve cover has a positioning seat with a through hole in the middle. The valve stem passes through the positioning seat through the through hole. A boss and a gasket are located on the front and rear sides of the positioning seat, respectively. A spring is located between the boss and the positioning seat. The valve cover clamps the outer end of the diaphragm between the valve body and the valve cover. The inner end of the diaphragm is located between the positioning seat and the gasket. The rear end face of the positioning seat and the front end face of the gasket are flat. The secondary check valve also includes a distributor located outside the valve seat and at the inlet end of the valve seat. The distributor has multiple through holes arranged in a circumferential direction, which connect to the vent.

[0003] Under normal water supply conditions, the primary valve core opens the inlet and closes the vent (the diaphragm contacts the valve seat and disengages from gasket one, while the diaphragm is also in close contact with the valve seat and distributor on the valve body). The secondary valve core opens the outlet, allowing water from the main water supply pipeline to enter the valve body through the inlet and flow out through the primary and secondary valve cores to supply water to the user. When water supply stops, gasket one moves the diaphragm forward, disengaging it from the valve seat, closing the inlet, opening the vent, and simultaneously closing the outlet. In this state, if backflow occurs in the pipeline after the secondary check valve, the backflow is blocked if the seal at the secondary valve core is intact. If the seal at the secondary valve core fails, the backflow enters the valve body through the outlet and is discharged through the distributor and vent to relieve pressure. Simultaneously, air enters the valve body through the vent, creating an air barrier to prevent backflow. If the seal at the first-stage valve core also fails at this time, the backflow water will not flow back to the inlet because the pressure has been released from the vent and air is isolated in the valve body.

[0004] However, the above-mentioned two-stage check valve also has its shortcomings: the diaphragm is fixed by clamping the valve body and the valve seat, while the first-stage check structure, which consists of valve stem one, gasket one, and spring one, is fixed by the positioning seat one inside the valve seat. That is to say, during installation, valve stem one, gasket one, and spring one must first be installed on the valve seat, and then the diaphragm is placed inside the valve seat. Then the valve seat and valve body are threaded together to clamp and fix the diaphragm. Obviously, this is quite inconvenient in assembly. Utility Model Content

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing an anti-backflow check valve, which solves the problem of inconvenient assembly.

[0006] The objective of this utility model can be achieved through the following technical solutions:

[0007] A backflow prevention check valve includes a valve body with a front end being an outlet and a rear end having an annular positioning seat, a valve seat threadedly connected to the rear end of the valve body, and a guide tube fixed within the valve body. The front end of the guide tube is located inside the outlet. A pressure relief port communicating with its inner cavity is provided on the side of the valve body. The valve body contains a first check assembly and a diaphragm whose front end abuts against the rear end of the guide tube. The first check assembly includes a first check spring, a first core rod passing through the diaphragm, and a first sealing plate fixed to the front end of the first core rod. The rear edge of the diaphragm abuts against the positioning seat. A second check spring is provided inside the outlet, abutting against the front end of the guide tube. The return assembly is characterized in that the valve body is provided with a water-passing plate, which is a metal part. The water-passing plate is fixedly connected to the rear end of the diaphragm. The front end of the valve seat directly or indirectly abuts against the rear side of the water-passing plate. The water-passing plate is provided with a central through hole and a plurality of water-passing holes arranged around the central through hole. The first core rod passes through the central through hole of the water-passing plate. The first check spring is sleeved on the rear end of the first core rod. The two ends of the first check spring abut against the rear end of the water-passing plate and the rear end of the first core rod, respectively. An annular protrusion is provided on the front side of the water-passing plate near the outer edge. An annular groove is provided at the rear end of the diaphragm. The annular protrusion is fixedly connected in the annular groove.

[0008] During normal water use, the front end of the diaphragm rests against the rear end of the guide tube, isolating the inner hole of the guide tube from the pressure relief port. Under water pressure, the first core rod moves forward, moving the first sealing plate away from the diaphragm. The second check valve assembly activates, opening the front end of the guide tube. Water flows in from the inlet and into the guide tube, then flows from the guide tube into the outlet. After water use ceases, the first core rod moves backward under the action of the first check spring, causing the first sealing plate to rest against the diaphragm again, and the second check valve assembly rests against the front end of the guide tube again. When water flows backward from the pipe network upstream of the anti-backflow check valve, if the seal at the second check valve assembly is completely intact, the backflowing water is blocked by the second check valve assembly and will not enter the valve body. If the seal at the second check assembly fails, causing a seal failure between the second check assembly and the front end of the guide tube, backflow water will enter the guide tube. The pressure of this backflow water acts on the diaphragm, causing it to be deformed backward. This causes the diaphragm to separate from the rear end of the guide tube, allowing the backflow water to flow into the valve body and be discharged through the pressure relief port. During this backward deformation of the diaphragm, the first sealing plate remains pressed against the diaphragm under the action of the first check spring.

[0009] This anti-backflow check valve features a water-passing plate within the valve body. This plate guides the movement of the first core rod, eliminating the need for the valve seat to guide its movement. The water-passing plate is also fixedly connected to the rear end of the diaphragm (it is a metal component, and the diaphragm is integrally formed onto it via vulcanization). This design integrates the diaphragm, water-passing plate, and first check assembly into a single unit, allowing for modular installation within the valve body. This simultaneous installation of the diaphragm and first check assembly significantly improves the ease of assembly. Furthermore, during diaphragm deformation, there is a pull towards the centerline. An annular protrusion is provided on the front side of the water-passing plate near the outer edge. After the diaphragm is integrally vulcanized onto the water-passing plate, an annular groove forms that mates with this protrusion. This fit increases the diaphragm's resistance to pull towards the centerline, preventing the diaphragm from detaching from the water-passing plate due to frequent deformation during long-term use.

[0010] In the aforementioned anti-backflow check valve, the rear end of the diaphragm has a rim that covers the edge of the water tray.

[0011] The above settings make the connection between the diaphragm and the water tray more secure, and make it less likely for the diaphragm to detach from the water tray during long-term use.

[0012] In the aforementioned anti-backflow check valve, the diaphragm is a cylindrical shape that gradually increases in size from front to back. An annular shoulder is provided on the inner side of the front end of the diaphragm. The first core rod passes through the central hole of the annular shoulder. The first sealing plate abuts against the annular shoulder to seal its central hole. The annular shoulder abuts against the rear end of the guide tube. An annular metal support plate is wrapped inside the annular shoulder.

[0013] The diaphragm is designed as a cylindrical shape that gradually increases in size from front to back. The inner side of the front end of the diaphragm has an annular shoulder, and an annular metal support plate is wrapped inside the annular shoulder. The metal support plate can support the annular shoulder. The cylindrical shape that is smaller at the front and larger at the back, combined with the setting of the metal support plate, ensures that the diaphragm can only deform in the direction of overall compression under the pressure of backflowing water. This prevents the diaphragm from collapsing on one side and causing leakage between it and the first sealing plate, thus improving the reliability of the operation.

[0014] In the aforementioned anti-backflow check valve, the outer periphery of the front end of the first core rod is provided with an abutment step, the first sealing plate is flat and abuts against the abutment step, the front end of the first core rod is also fitted with a first metal gasket, the first metal gasket is conical and the large end of the first metal gasket is facing forward, the central area of ​​the first metal gasket abuts against the first sealing plate, and the front end of the first core rod is fixedly connected with a first positioning screw, the head of the first positioning screw abuts against the first metal gasket.

[0015] The first sealing plate is flat and the first metal gasket is conical with its large end facing forward. This creates a space between the rear end of the first metal gasket and the first sealing plate, allowing the first sealing plate to deform forward. Therefore, when the first sealing plate abuts against the annular shoulder of the diaphragm, as the internal pressure of the valve body increases, the first sealing plate can deform using this space and be pressed into the central hole of the annular shoulder, thus creating a better seal between the first sealing plate and the annular shoulder.

[0016] In the aforementioned anti-backflow check valve, the valve body is provided with a pressure spring and a pressure ring, the guide tube is located inside the pressure spring, the front end of the pressure spring abuts against the inner wall of the valve body, and the pressure ring abuts against the rear end of the pressure spring and the front side of the diaphragm.

[0017] The pressure ring rests between the rear end of the pressure spring and the front side of the diaphragm. This allows the pressure ring and the spring force to protect the diaphragm and prevent excessive deformation of the diaphragm when the inlet water pressure increases suddenly.

[0018] Compared with existing technologies, this anti-backflow check valve features a water-passing plate within the valve body. This water-passing plate provides a guiding position for the first core rod, eliminating the need for the valve seat to guide the first core rod. Furthermore, the water-passing plate is fixedly connected to the rear end of the diaphragm (the water-passing plate is a metal component, and the diaphragm can be integrally molded onto the water-passing plate via vulcanization). This design integrates the diaphragm, water-passing plate, and first check assembly into a single, modular unit, allowing for modular installation and simultaneous installation of the diaphragm and first check assembly within the valve body. This significantly improves the ease of assembly for this anti-backflow check valve. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of Embodiment 1 of the anti-backflow check valve.

[0020] Figure 2 yes Figure 1 A magnified view of a section of the diaphragm.

[0021] Figure 3 This is a cross-sectional view of the components consisting of the diaphragm, the water tray, and the first check assembly in Embodiment 2 of this anti-backflow check valve.

[0022] In the diagram, 1. Valve body; 1a. Positioning seat; 1b. Pressure relief port; 2. Valve seat; 3. Flow guide tube; 4. Diaphragm; 4a. Annular groove; 4b. Annular shoulder; 4c. Edge band; 5. First check valve assembly; 6. First core rod; 7. First check valve spring; 8. First sealing plate; 9. Water passage plate; 9a. Central through hole; 9b. Water passage hole; 9c. Annular protrusion; 10. Metal support plate; 11. First metal gasket; 12. First positioning screw; 13. Compression spring; 14. Compression ring; 15. Second check valve assembly; 16. Front connecting pipe; 17. Front sealing gasket; 18. Rear connecting pipe; 19. Flow guide bracket; 20. Second core rod; 21. Second check valve spring; 22. Second metal gasket; 23. Second sealing plate; 24. Guide frame; 25. Second positioning screw. Detailed Implementation

[0023] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0024] Example 1

[0025] like Figure 1 and Figure 2As shown, an anti-backflow check valve includes a valve body 1 with a water outlet at the front end, a valve seat 2 threaded to the rear end of the valve body 1, and a guide cylinder 3 fixed inside the valve body 1. The front end of the guide cylinder 3 is located inside the water outlet, and a pressure relief port 1b communicating with its inner cavity is provided on the side of the valve body 1. A diaphragm 4 and a first check assembly 5 are provided inside the valve body 1. The diaphragm 4 is located behind the guide cylinder 3, and the front end of the diaphragm 4 abuts against the rear end of the guide cylinder 3. The first check assembly 5 includes a first core rod 6 passing through the diaphragm 4, a first check spring 7, and a first sealing plate 8 fixed to the front end of the first core rod 6. A second check assembly 15 is provided inside the water outlet, abutting against the front end of the guide cylinder 3.

[0026] like Figure 1 and Figure 2 As shown, the valve body 1 has a water-passing plate 9 inside. The water-passing plate 9 is a metal part and is fixedly connected to the rear end of the diaphragm 4. The rear end of the valve body 1 has an annular positioning seat 1a. The rear edge of the diaphragm 4 abuts against the positioning seat 1a. The front end of the valve seat 2 directly or indirectly abuts against the rear side of the water-passing plate 9. The water-passing plate 9 is provided with a central through hole 9a and several water passage holes 9b arranged around the central through hole 9a. The first core rod 6 passes through the central through hole 9a of the water-passing plate 9. The first check spring 7 is sleeved on the rear end of the first core rod 6. The two ends of the first check spring 7 abut against the rear ends of the water-passing plate 9 and the first core rod 6, respectively. An annular protrusion 9c is provided on the front side of the water-passing plate 9 near the outer edge. An annular groove 4a is provided at the rear end of the diaphragm 4. The annular protrusion 9c is fixedly connected in the annular groove 4a. The diaphragm 4 is a cylindrical shape that gradually increases in size from front to back. The inner side of the front end of the diaphragm 4 is provided with an annular shoulder 4b. The first core rod 6 passes through the central hole of the annular shoulder 4b. The first sealing plate 8 abuts against the annular shoulder 4b and seals its central hole. The annular shoulder 4b abuts against the rear end of the guide tube 3. The annular shoulder 4b is covered with an annular metal support plate 10. The outer periphery of the front end of the first core rod 6 is provided with an abutment step. The first sealing plate 8 is flat and abuts against the abutment step. The front end of the first core rod 6 is also fitted with a first metal gasket 11. The first metal gasket 11 is conical and the large end of the first metal gasket 11 faces forward. The central area of ​​the first metal gasket 11 abuts against the first sealing plate 8. The front end of the first core rod 6 is fixedly connected with a first positioning screw 12. The head of the first positioning screw 12 abuts against the first metal gasket 11. The valve body 1 is also provided with a pressure spring 13 and a pressure ring 14. The guide tube 3 is located inside the pressure spring 13. The front end of the pressure spring 13 abuts against the inner wall of the valve body 1. The pressure ring 14 is abutted between the rear end of the pressure spring 13 and the front side of the diaphragm 4.

[0027] Furthermore, such as Figure 1As shown, a second check valve assembly 15 is provided inside the outlet end, and the second check valve assembly 15 abuts against the front end of the guide tube 3 to seal it. The front end of the valve body 1 is connected to the front pipe 16 through the front swivel cap, and the rear end of the valve seat 2 is connected to the rear pipe 18 through the rear swivel cap. A front sealing gasket 17 is provided between the rear end of the front pipe 16 and the front end of the valve body 1. A guide support 19 is provided inside the front end of the valve body 1. The guide support 19 has a circular plate and several legs. The front end of each leg is bent inward and integrally fixed to the edge of the circular plate. The part formed by each leg is in clearance fit with the inner wall of the front end of the valve body 1, and the bent part of the front end of each leg abuts against the front sealing gasket 17. In this embodiment, the outer periphery of the front end of the guide tube 3 has an annular convex edge, and a sealing ring is sleeved on the outer side of the annular convex edge. The front end of the valve body 1 has an annular retaining edge, and the annular convex edge abuts against the front side of the retaining edge. Each leg of the guide bracket 19 abuts against the front side of the annular convex edge. Since the front end of the guide bracket 19 abuts against the front sealing gasket 17, the rear end of the guide bracket 19 abuts against the annular convex edge at the front end of the guide tube 3, and the annular convex edge abuts against the retaining edge inside the front end of the valve body 1, the guide tube 3 is thus fixed inside the valve body 1. The second check assembly 15 includes a second core rod 20 passing through a circular piece of the guide bracket 19 and a second check spring 21 sleeved on the second core rod 20. The front end of the second check spring 21 abuts against the circular piece, and the rear end of the second check spring 21 abuts against the second core rod 20. The rear end of the second core rod 20 is fitted with a second metal gasket 22 and a second sealing plate 23 sequentially from back to front. Both the second metal gasket 22 and the second sealing plate 23 are flat sheets. The second sealing plate 23 abuts against the front end of the guide tube 3. A guide frame 24 is slidably arranged inside the front end of the guide tube 3 along the front-rear direction. The guide frame 24 is a cylindrical shape with an open rear end. The front end of the guide frame 24 is fitted onto the rear end of the second core rod 20. The front end of the guide frame 24 abuts against the second sealing plate 23. The rear end of the second core rod 20 is threadedly connected with a second positioning screw 25. The head of the second positioning screw 25 abuts against the guide frame 24. The side of the guide frame 24 has several notches along the circumferential direction.

[0028] During normal water use, the annular shoulder 4b of the diaphragm 4 abuts against the rear end of the guide tube 3, isolating the inner hole of the guide tube 3 from the pressure relief port 1b. At this time, under the action of water pressure, the first core rod 6 moves forward, causing the first sealing plate 8 to move away from the diaphragm 4, and the second core rod 20 moves forward, causing the second sealing plate 23 to move away from the front end of the guide tube 3. Water flows in from the inlet end and enters the guide tube 3 through the central hole of the annular shoulder 4b on the diaphragm 4, and then flows from the guide tube 3 into the outlet end.

[0029] After water usage is stopped, the first core rod 6 moves backward under the action of the first check spring 7, causing the first sealing plate 8 to abut against the annular shoulder 4b of the diaphragm 4, thus sealing its central hole. The second core rod 20 moves backward under the action of the second check spring 21, causing the second sealing plate 23 to abut against the front end of the guide tube 3, thus sealing it. When water flows backward from the pipe network in front of the anti-backflow check valve, if the second sealing plate 23 is completely intact, the backflowing water will be blocked by the second check assembly 15 and will not enter the valve body 1. If the second sealing plate 23 is damaged, causing the seal between the second check assembly 15 and the guide tube 3 to fail, the backflowing water will enter the guide tube 3. At this time, the pressure of the backflowing water acts on the annular shoulder 4b of the diaphragm 4, causing the diaphragm 4 to be squeezed and deformed backward. In this way, the annular shoulder 4b of the diaphragm 4 will separate from the rear end of the guide tube 3, allowing the backflowing water to flow into the pressure relief chamber and be discharged from the pressure relief port 1b. During the process of the diaphragm 4 being squeezed and deformed backward, the first sealing piece 8 is always pressed against the annular shoulder 4b of the diaphragm 4 under the action of the first check spring 7.

[0030] This anti-backflow check valve has a water-passing plate 9 abutting between the diaphragm 4 and the valve cover. The water-passing plate 9 provides a guiding position for the first core rod 6, so the valve cover no longer serves to guide the first core rod 6. At the same time, the diaphragm 4 is integrally fixed to the water-passing plate 9, thus making the diaphragm 4, the water-passing plate 9 and the first check assembly 5 a single integrated component. This allows for modular installation and fixation within the valve body 1, achieving synchronous installation of the diaphragm 4 and the first check assembly 5 within the valve body 1, greatly improving the assembly convenience of this anti-backflow check valve.

[0031] Furthermore, the diaphragm 4 is designed as a cylindrical shape that gradually increases in size from front to back. The inner side of the front end of the diaphragm 4 has an annular shoulder 4b, and an annular metal support plate 10 is wrapped inside the annular shoulder 4b. The metal support plate 10 can support the annular shoulder 4b. The cylindrical shape that is smaller at the front and larger at the back, combined with the setting of the metal support plate 10, ensures that the diaphragm 4 can only deform in the direction of overall compression under the pressure of the backflowing water. This prevents the diaphragm 4 from collapsing on one side and causing a leak between it and the first sealing plate 8, thus improving the reliability of the operation.

[0032] Example 2

[0033] This embodiment is basically the same as embodiment one in structure and principle, except that: Figure 3 As shown, in this embodiment, the rear end of the diaphragm 4 has a rim 4c that covers the edge of the water tray 9.

[0034] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A backflow prevention check valve, comprising a valve body (1) with a front end being an outlet and a rear end having an annular positioning seat (1a), a valve seat (2) threadedly connected to the rear end of the valve body (1), and a guide tube (3) fixed inside the valve body (1), wherein the front end of the guide tube (3) is located inside the outlet, a pressure relief port (1b) communicating with its inner cavity is provided on the side of the valve body (1), a first check assembly (5) and a diaphragm (4) whose front end abuts against the rear end of the guide tube (3) are provided inside the valve body (1), the first check assembly (5) includes a first check spring (7), a first core rod (6) passing through the diaphragm (4), and a first sealing plate (8) fixed to the front end of the first core rod (6), the rear edge of the diaphragm (4) abuts against the positioning seat (1a), and a second check assembly (15) abutting against the front end of the guide tube (3) is provided inside the outlet, characterized in that, The valve body (1) is provided with a water-passing plate (9), which is a metal part. The water-passing plate (9) is fixedly connected to the rear end of the diaphragm (4). The front end of the valve seat (2) directly or indirectly abuts against the rear side of the water-passing plate (9). The water-passing plate (9) is provided with a central through hole (9a) and a number of water-passing holes (9b) arranged around the central through hole (9a). The first core rod (6) passes through the central through hole (9a) of the water-passing plate (9). The first check spring (7) is sleeved on the rear end of the first core rod (6). The two ends of the first check spring (7) abut against the rear end of the water-passing plate (9) and the first core rod (6) respectively. The front side of the water-passing plate (9) near the outer edge is provided with an annular protrusion (9c). The rear end of the diaphragm (4) is provided with an annular groove (4a). The annular protrusion (9c) is fixedly connected in the annular groove (4a).

2. The anti-backflow check valve according to claim 1, characterized in that, The rear end of the diaphragm (4) has a rim (4c) that covers the edge of the water tray (9).

3. The anti-backflow check valve according to claim 2, characterized in that, The diaphragm (4) is a cylindrical shape that gradually increases in size from front to back. The inner side of the front end of the diaphragm (4) is provided with an annular shoulder (4b). The first core rod (6) passes through the central hole of the annular shoulder (4b). The first sealing plate (8) abuts against the annular shoulder (4b) to seal its central hole. The annular shoulder (4b) abuts against the rear end of the guide tube (3). The annular shoulder (4b) is covered with an annular metal support plate (10).

4. A backflow prevention check valve according to claim 1, 2, or 3, characterized in that, The front end of the first core rod (6) is provided with an abutment step on the outer periphery. The first sealing plate (8) is flat and abuts against the abutment step. The front end of the first core rod (6) is also fitted with a first metal gasket (11). The first metal gasket (11) is conical and the large end of the first metal gasket (11) faces forward. The central area of ​​the first metal gasket (11) abuts against the first sealing plate (8). The front end of the first core rod (6) is fixedly connected with a first positioning screw (12). The head of the first positioning screw (12) abuts against the first metal gasket (11).

5. A backflow prevention check valve according to claim 3, characterized in that, The valve body (1) is provided with a pressure spring (13) and a pressure ring (14). The guide tube (3) is located inside the pressure spring (13). The front end of the pressure spring (13) abuts against the inner wall of the valve body (1). The pressure ring (14) is abutted between the rear end of the pressure spring (13) and the front side of the diaphragm (4).

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