Low-resistance backflow preventer

Abstract

The utility model belongs to the technical field of valves, and discloses a low-resistance backflow preventer. The low-resistance backflow preventer comprises a main valve body; the water inlet valve is arranged in the main valve body, a water inlet cavity is formed by the water inlet valve and the main valve body, and a water inlet cavity water escape valve channel communicated with the water inlet cavity is formed in the main valve body; the water outlet valve is arranged in the main valve body, a water outlet cavity is formed by the water outlet valve and the main valve body, a water outlet cavity water escape valve channel communicated with the water outlet cavity is formed in the main valve body, and a middle cavity is formed between the water inlet valve and the water outlet valve; the water escape valve is arranged at an outlet of the middle cavity and located outside the main valve body, a water inlet communicating cavity, a middle communicating cavity and a water outlet communicating cavity are formed in an inner cavity of the water escape valve, the outlet end of a water inlet cavity water escape valve channel communicates with the water inlet communicating cavity, and the outlet end of a water outlet cavity water escape valve channel communicates with the water outlet communicating cavity; the outlet end of the middle cavity communicates with the middle communicating cavity, a first membrane is arranged between the water inlet communicating cavity and the middle communicating cavity, and a valve plate is arranged on the first membrane. The utility model has good stability.

Description

Technical Field

[0001] The utility model relates to the technical field of valves, in particular to a low-resistance backflow preventer. Background Art

[0002] The low resistance backflow preventer is a device consisting of two separated and independent water inlet and outlet check valves and a drain valve for fluid safety control. It can strictly limit the pressure water in the pipeline to flow in one direction, prevent the medium in the pipeline from flowing back, and avoid backflow pollution.

[0003] Chinese patent CN110617351A provides a low-resistance backflow preventer, whose valve body shell is connected to the drainer through an external stainless steel pipe. However, the stainless steel pipe is used as the control pipeline of the low-resistance backflow preventer, and is externally installed. During the transportation and installation of the product, the external control pipeline is easily damaged by collision, and during the normal operation of the low-resistance backflow preventer, the external control pipeline is also easily damaged, resulting in the failure of the low-resistance backflow preventer, and further causing environmental or water pollution. Utility Model Content

[0004] The utility model aims to provide a low-resistance backflow preventer, which can solve the technical problem in the prior art that the control pipeline of the low-resistance backflow preventer is easily damaged after the control pipeline is externally placed.

[0005] To achieve this purpose, the utility model adopts the following technical solutions:

[0006] Low resistance backflow preventer, including:

[0007] Main valve body;

[0008] A water inlet valve is arranged in the main valve body and forms a water inlet cavity with the main valve body. The main valve body is provided with a water inlet cavity drain valve channel communicating with the water inlet cavity.

[0009] A water outlet valve is arranged in the main valve body and forms a water outlet cavity with the main valve body. The main valve body is provided with a water outlet cavity drain valve channel communicating with the water outlet cavity. An intermediate cavity is provided between the water inlet valve and the water outlet valve.

[0010] a drain valve, arranged at the outlet of the intermediate cavity and outside the main valve body, wherein the inner cavity of the drain valve is provided with a water inlet communication cavity, an intermediate communication cavity and a water outlet communication cavity which are independent of each other, wherein the outlet end of the drain valve channel of the water inlet cavity is communicated with the water inlet communication cavity, the outlet end of the drain valve channel of the water outlet cavity is communicated with the water outlet communication cavity, the outlet end of the intermediate cavity is communicated with the intermediate communication cavity, a first diaphragm for separating the water inlet communication cavity and the intermediate communication cavity is provided between the water inlet communication cavity and the intermediate communication cavity, and a valve plate for controlling the opening and closing of the drain port of the drain valve is provided on the first diaphragm;

[0011] When the pressure in the water inlet chamber is greater than the pressure in the water outlet chamber, the first diaphragm can drive the valve plate to close the drain port; when the pressure in the water inlet chamber is less than the pressure in the water outlet chamber, the first diaphragm can drive the valve plate to open the drain port.

[0012] Preferably, the drain valve comprises:

[0013] a drain valve body, in which the inner cavity is arranged, the drain valve body is arranged at the outlet of the intermediate cavity, opposite ends of the drain valve body are provided with a drain valve body inlet and the drain port, the drain valve body inlet is communicated with the outlet of the intermediate communicating cavity, opposite sides of the drain valve body are provided with a first opening and a second opening, the drain valve body inlet, the first opening and the second opening are all communicated with the inner cavity, and the drain port can be selectively communicated with the inner cavity through the valve plate;

[0014] a first drain valve cover, which is disposed on the drain valve body and covers the first opening, and the first diaphragm is sandwiched between the first drain valve cover and the drain valve body;

[0015] A second drain valve cover is arranged on the drain valve body and covers the second opening. A second diaphragm is sandwiched between the second drain valve cover and the drain valve body. The second diaphragm separates the intermediate connecting cavity from the water outlet connecting cavity.

[0016] Preferably, a drain valve sealing ring is sandwiched between the drain valve body and the main valve body, and a first avoidance hole, a second avoidance hole and a third avoidance hole are provided on the drain valve sealing ring, the first avoidance hole is located at the outlet end of the drain valve channel of the water inlet chamber, the second avoidance hole is located at the outlet of the intermediate chamber, and the third avoidance hole is located at the outlet end of the drain valve channel of the water outlet chamber.

[0017] Preferably, the drain valve body comprises:

[0018] A cylinder body, fixedly disposed in the middle communication cavity, wherein the outlet of the cylinder body is communicated with the drain port;

[0019] The valve shaft is movably arranged in the inner cavity of the drain valve body along its own axial direction, the first diaphragm is connected to one end of the valve shaft, the second diaphragm is fixedly arranged at the other end of the valve shaft, the valve plate is arranged on the valve shaft and connected to the first diaphragm, and the valve plate is arranged opposite to the inlet of the cylinder;

[0020] When the pressure in the water inlet chamber is greater than the pressure in the water outlet chamber, the first diaphragm can push the valve shaft to move toward the second diaphragm, so that the valve plate abuts against the inlet of the cylinder and blocks the inlet of the cylinder;

[0021] When the pressure in the water inlet chamber is lower than the pressure in the water outlet chamber, the second diaphragm pushes the valve shaft to move, so that the valve shaft pushes the first diaphragm to move away from the second diaphragm, thereby separating the valve plate from the inlet of the cylinder.

[0022] Preferably, a drain port seal is provided on a surface of the valve plate opposite to the inlet of the cylinder, and the drain port seal can abut against or separate from the inlet of the cylinder.

[0023] Preferably, the valve shaft comprises:

[0024] Valve shaft body;

[0025] The first diaphragm mounting body is slidable along the axial direction of the valve shaft body or fixedly arranged at one end of the valve shaft body, the first diaphragm and the valve plate are both fixedly installed on the first diaphragm mounting body, and the second diaphragm is fixedly arranged at the other end of the valve shaft body.

[0026] Preferably, a positioning flange and a first fastening ring are arranged at intervals on the outer periphery of the first diaphragm mounting body, the first diaphragm is clamped between the valve plate and the first fastening ring, a drain port seal is clamped between the valve plate and the positioning flange, and the drain port seal can abut against or separate from the inlet of the cylinder.

[0027] Preferably, a second fastening ring and a third fastening ring are provided at the other end of the valve shaft body, and the second diaphragm is clamped between the second fastening ring and the third fastening ring.

[0028] Preferably, the valve shaft body moves through the cylinder.

[0029] Preferably, a first flow channel is provided on the valve cover of the first drain valve, the inlet end of the first flow channel is communicated with the drain valve channel of the water cavity, and the outlet end of the first flow channel is communicated with the water inlet communication cavity;

[0030] The second drain valve cover is provided with a second flow channel, the inlet end of the second flow channel is communicated with the drain valve channel of the water outlet cavity, and the outlet end of the second flow channel is communicated with the water outlet communication cavity.

[0031] Beneficial effects of the utility model:

[0032] The low-resistance backflow preventer is provided with a water inlet chamber drain valve channel connected with the water inlet chamber on the main valve body, and the outlet end of the water chamber drain valve channel is connected with the water inlet connecting chamber of the drain valve; a water outlet chamber drain valve channel connected with the water outlet chamber is provided on the main valve body, and the outlet end of the water outlet chamber drain valve channel is connected with the water outlet connecting chamber of the drain valve.

[0033] The water inlet chamber drain valve channel and the water outlet chamber drain valve channel play the role of the control pipeline in the prior art, and avoid the external control pipeline, thereby avoiding the technical problem that the external control pipeline is easily damaged or destroyed by collision, and ensuring the stability of the product.

[0034] When the low-resistance backflow preventer is working normally, the pressure in the water inlet chamber is greater than the pressure in the water outlet chamber, the water inlet valve and the water outlet valve are both opened, and at the same time the first diaphragm drives the valve plate to close the drain port.

[0035] If the pressure downstream is higher than the pressure upstream (that is, the pressure in the water inlet chamber is lower than the pressure in the water outlet chamber), the water inlet valve and the water outlet valve are controlled to be closed, and the first diaphragm drives the valve plate to open the drain port. At this time, the medium in the middle chamber is discharged from the drain port of the drain valve. The drain port forms an air partition to separate the upstream from the downstream, preventing the downstream medium from entering the upstream. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0037] Figure 1 It is a structural schematic diagram of a drain valve body provided by an embodiment of the utility model;

[0038] Figure 2 It is a cross-sectional schematic diagram of the low-resistance backflow preventer provided by an embodiment of the utility model in an initial state;

[0039] Figure 3 It is a cross-sectional schematic diagram of the low-resistance backflow preventer provided by the embodiment of the utility model in a normal water supply state;

[0040] Figure 4It is a cross-sectional schematic diagram of the low-resistance backflow preventer provided by the embodiment of the utility model when no water is used downstream;

[0041] Figure 5 It is a schematic diagram of the low-resistance backflow preventer provided by the embodiment of the utility model when the downstream pressure is greater than the upstream pressure;

[0042] Figure 6 yes Figure 5 The enlarged view of point A in the middle;

[0043] Figure 7 It is a schematic diagram of the cross-sectional structure of the drain port seal provided by an embodiment of the utility model;

[0044] Figure 8 It is a schematic diagram of the cross-sectional structure of a drain valve provided in an embodiment of the utility model.

[0045] In the figure:

[0046] 1. Main valve body; 11. Water inlet chamber; 12. Water outlet chamber; 13. Intermediate chamber; 14. Water chamber drain valve channel; 15. Water outlet chamber drain valve channel;

[0047] 2. Water inlet valve; 21. Water inlet check valve plate;

[0048] 3. Water outlet valve; 31. Water outlet check valve plate;

[0049] 4. Drain valve; 41. Water inlet connecting chamber; 42. Intermediate connecting chamber; 43. Water outlet connecting chamber; 44. First diaphragm; 45. Drain port; 46. Valve plate; 461. Drain port sealing member;

[0050] 47, drain valve body; 471, cylinder; 472, valve shaft; 4721, valve shaft body; 47211, second fastening ring; 47212, third fastening ring; 4722, first diaphragm mounting body; 47221, positioning flange; 47222, first fastening ring; 473, third flow channel; 474, fourth flow channel; 475, drain valve spring; 476, mounting protrusion; 477, drain valve body inlet; 478, first opening; 479, second opening;

[0051] 48, first drain valve cover; 481, first flow channel; 49, second drain valve cover; 491, second diaphragm; 492, second flow channel;

[0052] 5. Drain valve sealing ring; 51. First avoidance hole; 52. Second avoidance hole; 53. Third avoidance hole. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0054] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0056] In the description of this embodiment, the terms "upper", "lower", "right", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0057] See also Figure 1-Figure 8 , this embodiment provides a low resistance backflow preventer. Specifically, the low resistance backflow preventer is a low resistance backflow preventer.

[0058] Specifically, Figure 3-Figure 5 In the figure, the straight lines with arrows indicate the water flow path.

[0059] Specifically, see Figure 1 and Figure 2 The low resistance backflow preventer comprises a main valve body 1, a water inlet valve 2, a water outlet valve 3 and a drain valve 4.

[0060] The water inlet valve 2 is arranged in the main valve body 1 , and forms a water inlet chamber 11 with the main valve body 1 . The main valve body 1 is provided with a water inlet chamber drain valve channel 14 which is in communication with the water inlet chamber 11 .

[0061] The outlet valve 3 is arranged in the main valve body 1 to form an outlet cavity 12 with the main valve body 1 . The main valve body 1 is provided with an outlet cavity drain valve channel 15 communicating with the outlet cavity 12 . An intermediate cavity 13 is provided between the inlet valve 2 and the outlet valve 3 .

[0062] The drain valve 4 is arranged at the outlet of the intermediate cavity 13 and is located outside the main valve body 1. The inner cavity of the drain valve 4 is provided with an independent water inlet connecting cavity 41, an intermediate connecting cavity 42 and a water outlet connecting cavity 43. The outlet end of the water inlet cavity drain valve channel 14 is connected with the water inlet connecting cavity 41, the outlet end of the water outlet cavity drain valve channel 15 is connected with the water outlet connecting cavity 43, the outlet end of the intermediate cavity 13 is connected with the intermediate connecting cavity 42, and a first diaphragm 44 for separating the water inlet connecting cavity 41 and the intermediate connecting cavity 42 is provided between the two, and a valve plate 46 for controlling the opening and closing of the drain port 45 of the drain valve 4 is provided on the first diaphragm 44.

[0063] When the pressure in the water inlet chamber 11 is greater than the pressure in the water outlet chamber 12 , the first diaphragm 44 can drive the valve plate 46 to close the drain port 45 ; when the pressure in the water inlet chamber 11 is less than the pressure in the water outlet chamber 12 , the first diaphragm 44 can drive the valve plate 46 to open the drain port 45 .

[0064] It can be understood that the pressures of the water inlet chamber 11 and the water inlet connecting chamber 41 are equal; the pressures of the water outlet chamber 12 and the water outlet connecting chamber 43 are equal; when the middle chamber 13 and the middle connecting chamber 42 are connected, the pressures of the two are equal.

[0065] The low-resistance backflow preventer provided in this embodiment is provided with a water inlet chamber drain valve channel 14 connected with the water inlet chamber 11 on the main valve body 1, and the outlet end of the water chamber drain valve channel 14 is connected with the water inlet connecting chamber 41 of the drain valve 4; a water outlet chamber drain valve channel 15 connected with the water outlet chamber 12 is provided on the main valve body 1, and the outlet end of the water outlet chamber drain valve channel 15 is connected with the water outlet connecting chamber 43 of the drain valve 4.

[0066] The water inlet chamber drain valve channel 14 and the water outlet chamber drain valve channel 15 play the role of the control pipeline in the prior art, and avoid the externalization of the control pipeline, thereby avoiding the technical problem that the external control pipeline is easily damaged or destroyed by collision.

[0067] When the low resistance backflow preventer is working normally, see Figure 3 , the pressure in the water inlet chamber 11 is greater than the pressure in the water outlet chamber 12 , the water inlet valve 2 and the water outlet valve 3 are both opened, and at the same time the first diaphragm 44 drives the valve plate 46 to close the drain port 45 .

[0068] See also Figure 5 If the pressure downstream is higher than the pressure upstream (that is, the pressure in the water inlet chamber 11 is lower than the pressure in the water outlet chamber 12), the water inlet valve 2 and the water outlet valve 3 are controlled to be closed, and the first diaphragm 44 drives the valve plate 46 to open the drain port 45. At this time, the medium in the intermediate chamber 13 is discharged from the drain port 45 of the drain valve 4. The drain port 45 forms an air partition to separate the upstream from the downstream, preventing the downstream medium from entering the upstream.

[0069] Specifically, in this embodiment, the water inlet valve 2 and the water outlet valve 3 are both check valves. The water inlet valve 2 includes a water inlet check valve plate 21 , and the water outlet valve 3 includes a water outlet check valve plate 31 .

[0070] The water inlet check valve plate 21 can be Figure 3 The open state shown and Figure 4 The water outlet check valve plate 31 can switch between the closed states shown. Figure 3 The open state shown and Figure 4 toggles between the on and off states shown.

[0071] The structure and principle of the check valve belong to the prior art and will not be introduced in detail here.

[0072] Specifically, see Figure 1 and Figure 8 The drain valve 4 includes a drain valve body 47 , a first drain valve cover 48 and a second drain valve cover 49 .

[0073] An inner cavity is provided in the drain valve body 47. The drain valve body 47 is provided at the outlet of the middle cavity 13, and a drain valve body inlet 477 and a drain port 45 are provided at opposite ends of the drain valve body 47. The drain valve body inlet 477 is communicated with the outlet of the middle communication cavity 42, and a first opening 478 and a second opening 479 are provided at opposite sides of the drain valve body 47. The drain valve body inlet 477, the first opening 478 and the second opening 479 are all communicated with the inner cavity, and the drain port 45 can be selectively communicated with the inner cavity through the valve plate 46.

[0074] The first drain valve cover 48 is disposed on the drain valve body 47 and covers the first opening 478 . A first diaphragm 44 is sandwiched between the first drain valve cover 48 and the drain valve body 47 .

[0075] The second drain valve cover 49 is disposed on the drain valve body 47 and covers the second opening 479 . A second diaphragm 491 is sandwiched between the second drain valve cover 49 and the drain valve body 47 . The second diaphragm 491 separates the intermediate communication chamber 42 from the water outlet communication chamber 43 .

[0076] See also Figure 2-Figure 7A drain valve sealing ring 5 is sandwiched between the drain valve body 47 and the main valve body 1. The drain valve sealing ring 5 is provided with a first avoidance hole 51, a second avoidance hole 52 and a third avoidance hole 53. The first avoidance hole 51 is located at the outlet end of the drain valve channel 14 of the water inlet chamber, the second avoidance hole 52 is located at the outlet of the middle chamber 13, and the third avoidance hole 53 is located at the outlet end of the drain valve channel 15 of the water outlet chamber.

[0077] Specifically, see Figure 6 , an annular protrusion is arranged around the outlet of the intermediate cavity 13 on the main valve body 1, and a groove is formed around the annular protrusion. The drain valve seal ring 5 is installed in the groove, and the drain valve body 47 of the drain valve 4 is provided with an installation protrusion 476 that can be installed in the groove. Such an arrangement can fully ensure the installation position accuracy of the drain valve seal ring 5.

[0078] In the present embodiment, by providing the drain valve sealing ring 5, it is possible to avoid the outlet of the water inlet chamber drain valve channel 14, the outlet of the water outlet chamber drain valve channel 15 and the outlet of the intermediate chamber 13 on the main valve body 1 from being interconnected, and it is also possible to avoid the inlet of the water inlet connecting chamber 41, the inlet of the intermediate connecting chamber 42 and the inlet of the water outlet connecting chamber 43 from being interconnected, thereby fully ensuring that the water in the water inlet chamber drain valve channel 14 can only flow into the water inlet connecting chamber 41 and cannot flow into the intermediate connecting chamber 42 and the water outlet connecting chamber 43, fully ensuring that the water in the water outlet chamber drain valve channel 15 can only flow into the water outlet connecting chamber 43 and cannot flow into the intermediate connecting chamber 42 and the water inlet connecting chamber 41, and at the same time fully ensuring that the water in the intermediate chamber 13 can only flow into the intermediate connecting chamber 42 and cannot flow into the water inlet connecting chamber 41 and the water outlet connecting chamber 43.

[0079] Further, see Figure 8 The drain valve body 47 includes a cylinder 471 and a valve shaft 472 .

[0080] The cylinder 471 is fixedly disposed in the middle communication cavity 42 , and the outlet of the cylinder 471 is communicated with the drain port 45 .

[0081] The valve shaft 472 is movably arranged in the inner cavity of the drain valve body 47 along its own axial direction, the first diaphragm 44 is connected to one end of the valve shaft 472, the second diaphragm 491 is fixedly arranged at the other end of the valve shaft 472, the valve plate 46 is arranged on the valve shaft 472 and connected to the first diaphragm 44, and the valve plate 46 is arranged opposite to the inlet of the cylinder 471.

[0082] When the pressure in the water inlet chamber 11 is greater than the pressure in the water outlet chamber 12 , the first diaphragm 44 can push the valve shaft 472 to move toward the second diaphragm 491 , so that the valve plate 46 abuts against and blocks the inlet of the cylinder 471 .

[0083] When the pressure in the water inlet chamber 11 is lower than the pressure in the water outlet chamber 12 , the second diaphragm 491 pushes the valve shaft 472 to move, so that the valve shaft 472 pushes the first diaphragm 44 to move away from the second diaphragm 491 , thereby separating the valve plate 46 from the inlet of the cylinder 471 .

[0084] Preferably, in this embodiment, the inlet of the cylinder 471 and the inlet of the intermediate communication chamber 42 are not arranged opposite to each other, so that the valve plate 46 can quickly abut against or separate from the inlet of the cylinder 471 .

[0085] It should be noted that the cylinder 471 is integrally formed on the drain valve body 47 , and the valve shaft 472 is movably disposed on the cylinder 471 along its own axial direction.

[0086] Furthermore, in order to ensure the sealing performance when the drain port 45 is closed, a drain port seal 461 is provided on the surface of the valve plate 46 opposite to the inlet of the cylinder 471 , and the drain port seal 461 can abut against or separate from the inlet of the cylinder 471 .

[0087] Specifically, in this embodiment, the valve shaft 472 includes a valve shaft body 4721 and a first diaphragm mounting body 4722. The first diaphragm mounting body 4722 is slidable along the axial direction of the valve shaft body 4721 or is fixedly disposed at one end of the valve shaft body 4721, the first diaphragm 44 and the valve plate 46 are both fixedly mounted on the first diaphragm mounting body 4722, and the second diaphragm 491 is fixedly disposed at the other end of the valve shaft body 4721.

[0088] Preferably, the first diaphragm mounting body 4722 is slidably disposed at one end of the valve shaft body 4721 along the axial direction of the valve shaft body 4721 .

[0089] Under normal circumstances, when the pressure in the water inlet chamber 11 is lower than the pressure in the water outlet chamber 12, the second diaphragm 491 pushes the valve shaft body 4721 to move, so that the valve shaft body 4721 pushes the first diaphragm 44 to move away from the second diaphragm 491, thereby separating the valve plate 46 from the inlet of the cylinder 471. When the valve shaft body 4721 is stuck relative to the cylinder 471, the pressure in the water inlet chamber 11 is lower than the pressure in the water outlet chamber 12, and the pressure in the water inlet chamber 11 is also lower than the pressure in the intermediate chamber 13. At this time, under the action of the water pressure in the intermediate connecting chamber 42, the first diaphragm 44 moves away from the second diaphragm 491, thereby separating the valve plate 46 from the inlet of the cylinder 471.

[0090] The first diaphragm 44 and the valve plate 46 are both fixedly mounted on the first diaphragm mounting body 4722. The first diaphragm mounting body 4722 is slidably arranged on one end of the valve shaft body 4721 along the axial direction of the valve shaft body 4721 to avoid the movement of the valve shaft body 4721 and the delay of the low-resistance backflow preventer from failing.

[0091] Of course, in other embodiments, the first diaphragm mounting body 4722 may also be fixedly disposed at one end of the valve shaft body 4721. In this case, the first diaphragm mounting body 4722 and the valve shaft body 4721 move synchronously.

[0092] Furthermore, in order to ensure that the first diaphragm 44 and the valve plate 46 are installed in place and stably, the outer periphery of the first diaphragm mounting body 4722 is spaced apart with a positioning flange 47221 and a first fastening ring 47222, the first diaphragm 44 is clamped between the valve plate 46 and the first fastening ring 47222, and a drain port seal 461 is clamped between the valve plate 46 and the positioning flange 47221, and the drain port seal 461 can abut against or separate from the entrance of the cylinder 471.

[0093] In order to ensure that the second diaphragm 491 is installed in place and stably, a second fastening ring 47211 and a third fastening ring 47212 are provided at the other end of the valve shaft body 4721 , and the second diaphragm 491 is clamped between the second fastening ring 47211 and the third fastening ring 47212 .

[0094] Furthermore, in order to ensure the stability of the valve shaft body 4721 installed in the drain valve body 47, the valve shaft body 4721 moves through the cylinder 471. In this way, the first diaphragm 44, the cylinder 471 and the second diaphragm 491 can support the valve shaft body 4721 together.

[0095] Specifically, a first flow channel 481 is provided on the first drain valve cover 48 , an inlet end of the first flow channel 481 is communicated with the water cavity drain valve channel 14 , and an outlet end of the first flow channel 481 is communicated with the water inlet communication cavity 41 .

[0096] A second flow channel 492 is provided on the second drain valve cover 49 . The inlet end of the second flow channel 492 is communicated with the drain valve channel 15 of the water outlet cavity, and the outlet end of the second flow channel 492 is communicated with the water outlet communication cavity 43 .

[0097] Furthermore, the drain valve body 47 is provided with a third flow channel 473 and a fourth flow channel 474. The third flow channel 473 is connected between the inlet end of the first flow channel 481 and the water cavity drain valve channel 14; the fourth flow channel 474 is connected between the inlet end of the second flow channel 492 and the water outlet cavity drain valve channel 15.

[0098] Specifically, in this embodiment, water in the water chamber drain valve channel 14 passes through the first avoidance hole 51 to enter the third flow channel 473; water in the middle chamber 13 passes through the second avoidance hole 52 to enter the middle connecting chamber 42; water in the water outlet chamber drain valve channel 15 passes through the third avoidance hole 53 to enter the fourth flow channel 474.

[0099] Furthermore, in this embodiment, the drain valve 4 also includes a drain valve spring 475, one end of the drain valve spring 475 is fixedly connected to the inner surface of the second drain valve cover 49, and the other end of the drain valve spring 475 is fixedly connected to the third fastening ring 47212, and the valve shaft 472 can drive the drain valve spring 475 to expand and contract during the reciprocating movement.

[0100] Exemplarily, in this embodiment, the working principle of the low resistance backflow preventer is:

[0101] See also Figure 3 In the normal water supply state, part of the water flow entering the water inlet chamber 11 will enter the water inlet connecting chamber 41 through the water inlet chamber drain valve channel 14, the third flow channel 473 and the first flow channel 481 in sequence. The water flow entering the water inlet connecting chamber 41 exerts pressure on the first diaphragm 44, and at this time, the pressure in the water inlet chamber 11 is greater than the pressure in the water outlet chamber 12, so the pressure on the first diaphragm 44 under action is greater than the pressure on the second diaphragm 491 under action, and the valve plate 46 moves rightward to abut against the entrance of the cylinder 471, so that the drain port 45 is closed and the water flow cannot flow out from the drain port 45; in the process of the first diaphragm 44 driving the valve shaft 472 to move rightward, the drain valve spring 475 is compressed. At this time, the control water inlet check valve plate 21 is in an open state, the water outlet check valve plate 31 is in an open state, the upstream water flow enters the water inlet chamber 11, and most of the water flow flows to the water outlet chamber 12 through the intermediate chamber 13 to supply water to the downstream.

[0102] See also Figure 4 When the downstream does not need water supply, the valve plate 46 moves rightward to abut against the inlet of the cylinder 471, so that the drain port 45 is closed and water cannot flow out of the drain port 45; when the first diaphragm 44 drives the valve shaft 472 to move rightward, the drain valve spring 475 is compressed. At this time, the water inlet check valve plate 21 is controlled to be in an open state, and the water outlet check valve plate 31 is in a closed state.

[0103] See also Figure 5 , if the downstream pressure increases or the upstream pressure decreases, resulting in the downstream pressure being greater than the upstream pressure, at this time, the water inlet check valve plate 21 and the water outlet check valve plate 31 are both in a closed state; the downstream water flows into the water outlet chamber 12, and the water entering the water outlet chamber 12 enters the water outlet connecting chamber 43 through the water outlet chamber drain valve channel 15, the fourth flow channel 474, and the second flow channel 492, and exerts pressure on the second diaphragm 491 (the direction of pressure is Figure 5At the same time, the force acting on the first diaphragm 44 is smaller than the force acting on the second diaphragm 491, and under the elastic recovery force of the drain valve spring 475, the second diaphragm 491 drives the valve shaft 472 to move left, and the valve shaft 472 moving left drives the valve plate 46 to leave the entrance of the cylinder 471. At this time, the drain port 45 is opened, and the water in the middle cavity 13 is discharged from the drain port 45 of the drain valve 4. The drain port 45 forms an air partition to separate the upstream from the downstream, thereby preventing the downstream water from entering the upstream.

[0104] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the scope of protection of the present invention. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. Low resistance backflow preventer, It is characterized in that include: Main valve body (1); A water inlet valve (2) is arranged in the main valve body (1) and forms a water inlet chamber (11) with the main valve body (1); the main valve body (1) is provided with a water inlet chamber drain valve channel (14) which is in communication with the water inlet chamber (11); a water outlet valve (3) disposed in the main valve body (1) and forming a water outlet cavity (12) with the main valve body (1); a water outlet cavity drain valve channel (15) communicating with the water outlet cavity (12) is disposed on the main valve body (1); and an intermediate cavity (13) is disposed between the water inlet valve (2) and the water outlet valve (3); A drain valve (4) is arranged at the outlet of the intermediate cavity (13) and is located outside the main valve body (1); the inner cavity of the drain valve (4) is provided with a water inlet connecting cavity (41), an intermediate connecting cavity (42) and a water outlet connecting cavity (43) which are independent of each other; the outlet end of the drain valve channel (14) of the water inlet cavity is connected to the water inlet connecting cavity (41); the outlet end of the drain valve channel (15) of the water outlet cavity is connected to the water outlet connecting cavity (43); the outlet end of the intermediate cavity (13) is connected to the intermediate connecting cavity (42); a first diaphragm (44) is provided between the water inlet connecting cavity (41) and the intermediate connecting cavity (42) for separating the two; a valve plate (46) is provided on the first diaphragm (44) for controlling the opening and closing of the drain port (45) of the drain valve (4); When the pressure in the water inlet chamber (11) is greater than the pressure in the water outlet chamber (12), the first diaphragm (44) can drive the valve plate (46) to close the water drain port (45); when the pressure in the water inlet chamber (11) is less than the pressure in the water outlet chamber (12), the first diaphragm (44) can drive the valve plate (46) to open the water drain port (45).

2. The low resistance backflow preventer according to claim 1, It is characterized in that The drain valve (4) comprises: A drain valve body (47) having the inner cavity arranged therein, the drain valve body (47) being arranged at the outlet of the intermediate cavity (13), the drain valve body inlet (477) and the drain port (45) being arranged at opposite ends of the drain valve body (47), the drain valve body inlet (477) being in communication with the outlet of the intermediate connecting cavity (42), the drain valve body inlet (477) being in communication with the outlet of the intermediate connecting cavity (42), the drain valve body inlet (478) and the second opening (479) being arranged at opposite sides of the drain valve body (47), the drain valve body inlet (477), the first opening (478) and the second opening (479) being all in communication with the inner cavity, and the drain port (45) being capable of selectively communicating with the inner cavity through the valve plate (46); a first drain valve cover (48), which is arranged on the drain valve body (47) and covers the first opening (478), and the first diaphragm (44) is sandwiched between the first drain valve cover (48) and the drain valve body (47); A second drain valve cover (49) is arranged on the drain valve body (47) and covers the second opening (479); a second diaphragm (491) is sandwiched between the second drain valve cover (49) and the drain valve body (47); the second diaphragm (491) separates the intermediate connecting chamber (42) and the water outlet connecting chamber (43).

3. The low resistance backflow preventer according to claim 2, It is characterized in that A drain valve sealing ring (5) is sandwiched between the drain valve body (47) and the main valve body (1); a first avoidance hole (51), a second avoidance hole (52) and a third avoidance hole (53) are provided on the drain valve sealing ring (5); the first avoidance hole (51) is located at the outlet end of the drain valve channel (14) of the water inlet chamber, the second avoidance hole (52) is located at the outlet of the intermediate chamber (13), and the third avoidance hole (53) is located at the outlet end of the drain valve channel (15) of the water outlet chamber.

4. The low resistance backflow preventer according to claim 2, It is characterized in that The drain valve body (47) comprises: A cylinder (471) is fixedly disposed in the intermediate communication cavity (42), and an outlet of the cylinder (471) is communicated with the drain port (45); The valve shaft (472) is movably arranged in the inner cavity of the drain valve body (47) along its own axial direction, the first diaphragm (44) is connected to one end of the valve shaft (472), the second diaphragm (491) is fixedly arranged at the other end of the valve shaft (472), the valve plate (46) is arranged on the valve shaft (472) and connected to the first diaphragm (44), and the valve plate (46) is arranged opposite to the inlet of the cylinder (471); When the pressure in the water inlet chamber (11) is greater than the pressure in the water outlet chamber (12), the first diaphragm (44) can push the valve shaft (472) to move toward the second diaphragm (491), so that the valve plate (46) abuts against the inlet of the cylinder (471) and blocks the inlet of the cylinder (471); When the pressure in the water inlet chamber (11) is lower than the pressure in the water outlet chamber (12), the second diaphragm (491) pushes the valve shaft (472) to move, so that the valve shaft (472) pushes the first diaphragm (44) to move in a direction away from the second diaphragm (491), thereby separating the valve plate (46) from the inlet of the cylinder (471).

5. The low resistance backflow preventer according to claim 4, It is characterized in that A drain port seal (461) is provided on the surface of the valve plate (46) opposite to the inlet of the cylinder (471), and the drain port seal (461) can abut against or separate from the inlet of the cylinder (471).

6. The low resistance backflow preventer according to claim 4, It is characterized in that The valve shaft (472) comprises: Valve shaft body (4721); The first diaphragm mounting body (4722) is slidable along the axial direction of the valve shaft body (4721) or fixedly arranged at one end of the valve shaft body (4721), the first diaphragm (44) and the valve plate (46) are both fixedly installed on the first diaphragm mounting body (4722), and the second diaphragm (491) is fixedly arranged at the other end of the valve shaft body (4721).

7. The low resistance backflow preventer according to claim 6, It is characterized in that The outer periphery of the first diaphragm mounting body (4722) is spaced apart with a positioning flange (47221) and a first fastening ring (47222); the first diaphragm (44) is sandwiched between the valve plate (46) and the first fastening ring (47222); a drain port seal (461) is sandwiched between the valve plate (46) and the positioning flange (47221); the drain port seal (461) can abut against or separate from the inlet of the cylinder (471).

8. The low resistance backflow preventer according to claim 6, It is characterized in that The other end of the valve shaft body (4721) is provided with a second fastening ring (47211) and a third fastening ring (47212), and the second diaphragm (491) is clamped between the second fastening ring (47211) and the third fastening ring (47212).

9. The low resistance backflow preventer according to claim 6, It is characterized in that The valve shaft body (4721) moves through the cylinder (471).

10. The low resistance backflow preventer according to any one of claims 2 to 9, It is characterized in that The first drain valve cover (48) is provided with a first flow channel (481), the inlet end of the first flow channel (481) is communicated with the water cavity drain valve channel (14), and the outlet end of the first flow channel (481) is communicated with the water inlet communication cavity (41); The second drain valve cover (49) is provided with a second flow channel (492), the inlet end of the second flow channel (492) is connected to the drain valve channel (15) of the water outlet cavity, and the outlet end of the second flow channel (492) is connected to the water outlet communication cavity (43).

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