Low-resistance backflow preventer

Abstract

The invention discloses a low-resistance backflow preventer, and relates to the technical field of backflow preventers, the low-resistance backflow preventer comprises a main valve body, two elastic sealing check valves and a hydraulic differential type water escape valve, a sliding seat is slidably sleeved outside a valve rod between a valve seat and a valve plate, and an annular sealing air bag cushion is sleeved outside the sliding seat; a first spring is arranged between the sliding seat and the valve plate, a buffering assembly is arranged between the sliding seat and the valve seat, a plurality of water guide pipes are arranged between the water storage device and the sliding seat, an air guide pipe is arranged between the air inflation device and the sliding seat, the sealing air bag cushion is communicated with the air guide pipe through a mounting ring and the sliding seat, and annular protrusions are arranged on the inner surface of the first groove and the inner surface of the second groove. According to the elastic sealing check valve, the situation that impurities are clamped into the two sides of the sealing air bag cushion in the closing process of the elastic sealing check valve can be prevented, the sealing performance of the elastic sealing check valve can be effectively improved, liquid back seepage caused by poor sealing is prevented, and the purpose of automatically cleaning the impurities attached to the sealing air bag cushion can be achieved.

Description

Technical Field

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

[0002] The backflow preventer is a hydraulic control combination device that strictly limits the water in the pipeline to flow in one direction, developed based on the tap water supply equipment, especially the serious backflow pollution in the domestic drinking water pipeline, and the lack of effective backflow pollution prevention devices. Its function is to prevent the medium in the pipeline from flowing back under any working conditions to achieve the purpose of avoiding backflow pollution. At present, the backflow preventer is mainly divided into two types: low-resistance backflow preventer and pressure-reducing backflow preventer. The low-resistance backflow preventer is composed of two independent spring-assisted elastic sealing check valves and an independent hydraulic differential drain valve in the middle pressure-reducing chamber. The pressure chamber of the drain valve is connected to the upstream water supply pressure. The three internal valves have no mechanical connection except for the shared valve body, so there will be no common related mechanical failures at the same time, and each of them is guaranteed to act independently, strictly limiting the pressure water in the pipeline to flow in one direction.

[0003] However, the elastic sealing check valve in the low-resistance backflow preventer currently relies on the sealing gasket for sealing. However, during the closing process of the liquid backflow elastic sealing check valve, impurities such as stones in the water flow may be stuck between the sealing gasket and the valve seat, resulting in the elastic sealing check valve not being closed tightly enough. At this time, the backflowing liquid can flow back from the gap between the sealing gasket and the valve plate, thus affecting the failure of the backflow prevention function of the backflow preventer and causing a certain impact on normal operation. Moreover, the elastic sealing check valve only relies on a layer of sealing gasket to achieve the sealing and anti-backflow between the valve plate and the valve seat, and the sealing structure is relatively simple. Therefore, there is still the possibility of liquid backflow or backseepage, which is difficult to meet the use under the condition of high requirements for sealing. Moreover, after the sealing gasket has been used for a period of time, a layer of impurities is easily adhered to its outer surface. Therefore, the sealing gasket needs to be regularly maintained and replaced. The maintenance and replacement work is relatively cumbersome, and the maintenance is relatively frequent, which is bound to lead to more maintenance work in the later stage, which will not only waste a certain amount of manpower and material resources, but also affect the normal delivery of the liquid. Therefore, there is still room for improvement. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a low-resistance backflow preventer, which solves the problems raised in the background technology.

[0006] (II) Technical solution

[0007] To achieve the above object, the present invention provides the following technical solutions: a low resistance backflow preventer, comprising a main valve body, two elastic sealing check valves are arranged inside the main valve body, a hydraulic differential drain valve is arranged outside the main valve body, the elastic sealing check valve comprises a valve seat and a valve plate, a valve stem is fixedly connected to the outside of the valve plate, the valve stem is arranged on the valve seat, and a return spring is arranged between the valve stem and the valve seat;

[0008] The outside of the valve stem is sleeved and slidably connected with a sliding seat between the valve seat and the valve plate, the outside of the sliding seat is sleeved with an annular sealing airbag cushion, a first spring is provided between the sliding seat and the valve plate, and a buffer component is provided between the sliding seat and the valve seat;

[0009] The valve plate is provided with a water storage device connected to the slide seat on the outside, and a plurality of water pipes are provided between the water storage device and the slide seat. The outer surface of the slide seat is provided with a plurality of water holes, which are connected to the water pipes.

[0010] An air-filling device connected to the water storage device is provided outside the valve plate, an air guide tube is provided between the air-filling device and the slide seat, a mounting ring is provided between the inner hole wall of the sealed airbag cushion and the outer surface of the slide seat, and the sealed airbag cushion is connected to the air guide tube through the mounting ring and the slide seat;

[0011] A first groove matching the airbag seal cushion is formed on one side of the valve seat close to the valve plate, and a second groove matching the airbag seal cushion is formed on one side of the valve plate close to the valve seat. The inner surfaces of the first groove and the second groove are both provided with annular protrusions.

[0012] Preferably, the buffer assembly includes a pressure plate and a second spring, the pressure plate is slidably connected to the outside of the valve stem, and two ends of the second spring are respectively connected to the pressure plate and the sliding seat.

[0013] Preferably, the water storage device comprises a water storage cylinder, the interior of the water storage cylinder is slidably connected to a first piston, the exterior of the first piston is fixedly connected to a first piston rod, and the first piston rod is connected to a sliding seat by penetrating a valve plate.

[0014] Preferably, the water conduit is provided with a first corrugated section with a retractable length, and the first corrugated section is located between the valve plate and the sliding seat.

[0015] Preferably, the plurality of water holes are divided into two water hole groups, the two water hole groups are respectively located on both sides of the sealed airbag cushion, and the plurality of water holes in the two water hole groups are divergently distributed along the axis of the valve stem.

[0016] Preferably, the inflation device includes an air cylinder fixedly connected to the outer surface of the water storage device, the interior of the air cylinder is slidably connected to a second piston, the outside of the second piston is fixedly connected to a second piston rod, and the end of the second piston away from the second piston is fixedly connected to the first piston by being inserted into the water storage cylinder.

[0017] Preferably, an air hole is provided on the outer surface of the sliding seat, and an annular through groove is provided on the inner ring wall of the mounting ring, and the through groove is connected with the air guide tube through the air hole.

[0018] Preferably, a through hole is opened inside the mounting ring, the inner ring wall of the sealed airbag cushion is open, and the inner cavity of the airbag cushion is connected with the air hole through the inner ring wall opening and the through hole.

[0019] Preferably, the mounting ring is fixed to the outside of the slide seat by screw sleeve connection, and a sealing ring is provided between the inner ring wall of the mounting ring and the outer surface of the slide seat.

[0020] Preferably, the air guide pipe is provided with a second corrugated section, and the second corrugated section is located between the valve plate and the sliding seat.

[0021] (III) Beneficial effects

[0022] Compared with the prior art, the present invention provides a low-resistance backflow preventer, which has the following beneficial effects:

[0023] 1. To achieve the purpose of flushing the outer surface of the sealing airbag cushion during the resetting and closing process of the elastic sealing check valve, so that impurities such as gravel, mud and sand flowing into the space between the sealing airbag cushion and the valve plate and between the sealing airbag cushion and the valve seat can be flushed out of the elastic sealing check valve, and thereby prevent the situation where impurities are stuck in the two sides of the sealing airbag cushion during the closing process of the elastic sealing check valve, thereby preventing the water flow of the backflow preventer from flowing back or seeping back due to the stuck impurities, and ensuring the sealing effect of the elastic sealing check valve itself and the normal use of the backflow preventer.

[0024] 2. When the elastic sealing check valve is closed, the two sides of the sealing airbag cushion can be tightly attached to the valve plate and the valve seat respectively, which can effectively improve the sealing between the valve plate and the valve seat and the entire elastic sealing check valve. In addition, the squeezing force of the valve plate on the valve seat can make the sealing airbag cushion, the valve plate and the valve seat fit more closely, thereby further improving the sealing of the elastic sealing check valve, preventing liquid backseepage caused by poor sealing, and enabling the backflow preventer to better meet the use of high requirements for sealing.

[0025] 3. After the sealed airbag cushion is inflated, its outer surface area will increase, and its outer surface tension will also increase. At this time, the impurities adhering to the outer surface of the sealed airbag cushion will also be loosened. In this case, the outer surface of the sealed airbag cushion can be flushed with water flow from the water hole to wash away the loosened impurities and flush out the elastic sealing check valve, thereby achieving the purpose of automatically cleaning the magazines adhering to the sealed airbag cushion, thereby reducing the maintenance cycle of the sealed airbag cushion to a certain extent, and thus making the maintenance and replacement work not too cumbersome and frequent, and reducing the workload of later maintenance to a certain extent, making the later maintenance work more saving manpower and material resources, thereby avoiding affecting the normal transportation work.

[0026] 4. The provision of the first groove, the second groove and the protrusion can increase the sealing contact area between the sealing airbag cushion and the valve plate and between the sealing airbag cushion and the valve seat, and can also increase the close fit between the sealing airbag cushion and the valve plate and the valve seat respectively, and can enable the sealing airbag cushion to be retracted into the first groove and the second groove, so that the corresponding sides of the valve plate and the valve seat can also be closely fitted together, thereby further improving the sealing performance of the elastic sealing check valve, and thereby further improving the sealing performance of the entire backflow preventer. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic cross-sectional view of the elastic sealing check valve of the present invention in an open state;

[0028] Figure 2 It is a schematic cross-sectional view of the elastic sealing check valve of the present invention in a closed state;

[0029] Figure 3 It is a schematic diagram of the front view of the three-dimensional structure of the present invention;

[0030] Figure 4 It is a schematic diagram of the three-dimensional structure of the elastic sealing check valve in the present invention;

[0031] Figure 5 It is a schematic diagram of the three-dimensional structure of the elastic sealing check valve in the present invention;

[0032] Figure 6 It is a front view structural schematic diagram of the elastic sealing check valve in the present invention;

[0033] Figure 7 It is a front view cross-sectional structural schematic diagram of the elastic sealing check valve in the open state of the present invention;

[0034] Figure 8 It is a schematic diagram of the front cross-sectional structure of the elastic sealing check valve in the closed state of the present invention;

[0035] Fig. 9It is a schematic diagram of the three-dimensional structure of the valve seat in the present invention;

[0036] Fig.10 It is a schematic diagram of the three-dimensional structure of the slide seat in the present invention;

[0037] Fig.11 It is a schematic diagram of the three-dimensional structure of the valve plate in the present invention;

[0038] Fig.12 It is a schematic diagram of the three-dimensional structure of the sealed airbag cushion in the present invention;

[0039] Fig.13 It is a schematic diagram of a top cross-sectional structure of a sealed airbag cushion and an inflator in the present invention;

[0040] Fig.14 For the present invention Fig.13 Enlarged structural diagram at A in the middle.

[0041] In the figure: 1, main valve body; 2, elastic sealing check valve; 3, hydraulic differential drain valve; 4, valve seat; 401, first groove; 5, valve plate; 501, valve stem; 502, return spring; 503, second groove; 6, sealing airbag cushion; 601, mounting ring; 6011, through groove; 6012, through hole; 6013, sealing ring; 7, sliding seat; 701, water hole; 702, air hole; 8, water storage device 801, water storage cylinder; 802, first piston; 803, first piston rod; 9, inflation device; 901, air cylinder; 902, second piston; 903, second piston rod; 10, water guide pipe; 1001, first corrugated section; 11, air guide pipe; 1101, second corrugated section; 12, first spring; 13, pressure plate; 14, second spring; 15, protrusion; 16, valve cover; 17, detection port. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0044] In the present invention, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connect", "fix" and the like should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be a mechanical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0046] Embodiment 1

[0047] The present invention provides Figures 1 to 8 A low resistance backflow preventer is shown: comprising a main valve body 1, two elastic sealing check valves 2 are arranged inside the main valve body 1, a hydraulic differential drain valve 3 is arranged outside the main valve body 1, an inspection port is arranged outside the main valve body 1 between the two elastic sealing check valves 2, a valve cover 16 is installed outside the inspection port, and a detection port 17 is arranged outside the valve cover 16 and the main valve body 1;

[0048] The elastic sealing check valve 2 includes a valve seat 4 and a valve plate 5. The interior of the valve seat 4 is hollow to allow water to flow through. The valve seat 4 is installed inside the main valve body 1. The exterior of the valve plate 5 is fixedly connected with a valve stem 501. The valve stem 501 penetrates and slides on the valve seat 4. A return spring 502 is provided between the valve stem 501 and the valve seat 4.

[0049] The outside of the valve stem 501 is sleeved and slidably connected with a slide seat 7 between the valve seat 4 and the valve plate 5. The outside of the slide seat 7 is sleeved with an annular sealing airbag cushion 6. A first spring 12 is provided between the slide seat 7 and the valve plate 5, and a buffer component is provided between the slide seat 7 and the valve seat 4.

[0050] The buffer assembly includes a pressure plate 13 and a second spring 14. The pressure plate 13 is slidably connected to the outside of the valve stem 501. Both ends of the second spring 14 are respectively connected to the pressure plate 13 and the sliding seat 7.

[0051] The outside of the valve plate 5 is provided with a water storage device 8 connected to the slide seat 7, and six water guide pipes 10 are provided between the water storage device 8 and the slide seat 7. The water guide pipe 10 is provided with a first corrugated section 1001 with a retractable length. The first corrugated section 1001 is located between the valve plate 5 and the slide seat 7, and the inside of the valve plate 5 is provided with a receiving cavity for accommodating the first corrugated section 1001. The outer surface of the slide seat 7 is provided with twelve water holes 701, and the twelve water holes 701 are divided into two groups of water holes of equal number. The two groups of water holes are respectively located on both sides of the sealing airbag cushion 6. The six water holes 701 in the two groups of water holes are divergently distributed along the axis of the valve stem 501, and the six water holes 701 in the two groups of water holes are respectively connected with the six water guide pipes 10;

[0052] The water storage device 8 includes a water storage cylinder 801 , the interior of the water storage cylinder 801 is slidably connected to a first piston 802 , the exterior of the first piston 802 is fixedly connected to a first piston rod 803 , and the first piston rod 803 is connected to the slide seat 7 by penetrating the valve plate 5 .

[0053] The working principle is: the initial state of the backflow preventer is as follows: Figure 2 As shown, when water flows into the main valve body 1 from the left inlet, the water flow direction is as follows: Figure 1 As shown in the direction indicated by the arrow, the water pressure of the water flow will open the elastic sealing check valve 2 near the left side, and enter the cavity between the two elastic sealing check valves 2 in the main valve body 1, and then the water flow will continue to flow to the right side, and open the elastic sealing check valve 2 on the right side by its water pressure, and thus flow out of the backflow preventer through the outlet on the right side of the main valve body 1, and when the inflow water pressure decreases, the two elastic sealing check valves 2 will automatically close, thereby preventing the water flow from flowing back;

[0054] Moreover, if Figure 8 As shown, in the initial state of the backflow preventer, the return spring 502 is in a certain compression state but not completely compressed. At this time, the return spring 502 can apply a pulling force to the valve plate 5 through the valve stem 501, thereby pressing the valve plate 5 on the sealing airbag cushion 6 and the valve seat 4, thereby realizing the sealing of the elastic sealing check valve 2, and under the pressure of the valve plate 5, the second spring 14 will be compressed by the pressure plate 13 and the slide seat 7, and the first spring 12 will be compressed by the valve plate 5 and the slide seat 7;

[0055] In the process of opening the elastic sealing check valve 2 (the state of the elastic sealing check valve 2 after opening is as follows Figure 7As shown in the figure, the water flow will first flow through the valve seat 4 through the cavity in the valve seat 4, and exert a thrust on the sealing airbag cushion 6 and the valve plate 5 through the water pressure, thereby pushing the sealing airbag cushion 6 and the valve plate 5 to the right. At this time, the water flow can flow through the gap between the valve plate 5 and the valve seat 4. In the process of the sealing airbag cushion 6 and the valve plate 5 being pushed by the water flow, the first spring 12 and the second spring 14 will restore to their original lengths under the action of their own rebound forces. Therefore, the second spring 14 can increase the distance between the pressure plate 13 and the slide seat 7 through the rebound thrust, and the first spring 12 can also increase the distance between the slide seat 7 and the sealing airbag cushion 6 through the rebound thrust. The distance between the airbag cushion 6 and the valve plate 5 increases. Since the water storage cylinder 801 also moves synchronously with the valve plate 5, the slide seat 7 can drive the first piston 802 to slide relatively between the water storage cylinder 801 and the water storage cylinder 801 through the first piston rod 803 during this process, thereby increasing the distance between the first piston 802 and the bottom wall of the water storage cylinder 801, and forming a negative pressure in the cavity between the first piston 802 and the bottom wall of the water storage cylinder 801, thereby absorbing water in the main valve body 1 through the water conduit 10 and the water hole 701, and sucking the water into the water storage cylinder 801, so as to achieve the purpose of water storage;

[0056] When the water pressure entering the main valve body 1 decreases, the water pressure on the valve plate 5 will also decrease. At this time, the elastic sealing check valve 2 will be reset and closed under the rebound force of the reset spring 502. Specifically, the reset spring 502 will reset the sealing airbag cushion 6, the slide seat 7, the valve plate 5 and the water storage cylinder 801 by pushing the valve stem 501. In this process, the slide seat 7 will also squeeze the first piston 802 through the first piston rod 803 and reset the first piston 802, so that the water previously sucked into the water storage cylinder 801 will be ejected through the water pipe 10 and the water hole 701 in sequence. Moreover, the outlets of the water holes 701 in the two groups of water holes are respectively directed toward the two side surfaces of the sealed airbag cushion 6, so that the sprayed water flow can directly flush the two side surfaces of the sealed airbag cushion 6, thereby achieving the purpose of flushing the outer surface of the sealed airbag cushion 6 during the process of the elastic sealing check valve 2 being reset and closed. Therefore, impurities such as gravel, mud and sand that flow into the space between the sealed airbag cushion 6 and the valve plate 5 and between the sealed airbag cushion 6 and the valve seat 4 can be flushed out of the elastic sealing check valve 2, thereby preventing the situation in which impurities are stuck on both sides of the sealed airbag cushion 6 during the closing process of the elastic sealing check valve 2.

[0057] Furthermore, the first corrugated section 1001 on the water pipe 10 can ensure that the water pipe 10 has a certain telescopic function, so that the water pipe 10 can also maintain communication with the water hole 701 on the slide seat 7 during the change of the distance between the slide seat 7 and the valve plate 5 .

[0058] Embodiment 2

[0059] The present invention provides Figures 7 to 14A low resistance backflow preventer is shown: an air filling device 9 connected to a water storage device 8 is provided outside the valve plate 5, an air guide tube 11 is provided between the air filling device 9 and the slide seat 7, a second corrugated section 1101 is provided on the air guide tube 11, the second corrugated section 1101 is located between the valve plate 5 and the slide seat 7, and the second corrugated section 1101 is also located in the accommodating cavity of the valve plate 5, a mounting ring 601 is provided between the inner hole wall of the sealing airbag cushion 6 and the outer surface of the slide seat 7, and the sealing airbag cushion 6 is connected to the air guide tube 11 through the mounting ring 601 and the slide seat 7;

[0060] The inflating device 9 includes an air cylinder 901 fixedly connected to the outer surface of the water storage device 8, the interior of the air cylinder 901 is slidably connected to a second piston 902, the exterior of the second piston 902 is fixedly connected to a second piston rod 903, the end of the second piston 902 away from the second piston 902 is fixedly connected to the first piston 802 by being inserted into the water storage cylinder 801, and a sliding sealing ring is provided between the second piston rod 903 and the water storage cylinder 801;

[0061] An air hole 702 is formed on the outer surface of the sliding seat 7, an annular through groove 6011 is formed on the inner ring wall of the mounting ring 601, the through groove 6011 is communicated with the air guide tube 11 through the air hole 702, a through hole 6012 is formed inside the mounting ring 601, the inner ring wall of the sealed airbag cushion 6 is open, and the inner cavity of the sealed airbag cushion 6 is communicated with the air hole 702 through the inner ring wall opening and the through hole 6012;

[0062] The mounting ring 601 is fixed to the outside of the slide seat 7 by screw sleeve connection, and a sealing ring 6013 is provided between the inner ring wall of the mounting ring 601 and the outer surface of the slide seat 7;

[0063] The working principle is as follows: during the opening of the elastic sealing check valve 2, the distance between the first piston 802 and the inner bottom wall of the water storage cylinder 801 will increase, and the first piston 802 is connected to the second piston rod 903, and the air cylinder 901 is fixedly installed on the outside of the water storage cylinder 801. Therefore, during this process, the first piston 802 can drive the second piston 902 to slide relatively in the air cylinder 901 and between the air cylinder 901 through the second piston rod 903, and increase the distance between the inner bottom wall of the air cylinder 901 and the second piston 902, and thereby evacuate the hollow inner cavity of the sealed airbag cushion 6 through the air guide pipe 11, the air hole 702, the through groove 6011 and the through hole 6012 in sequence. The evacuated sealed airbag cushion 6 has a shape as shown in FIG. Figure 6 as well as Figure 7As shown; when the elastic sealing check valve 2 is closed, the first piston 802 will be reset, and at this time, the first piston 802 will also drive the second piston 902 to reset in the air cylinder 901 through the second piston rod 903, and the air between the second piston 902 and the inner bottom wall of the air cylinder 901 will be filled into the sealed airbag cushion 6 through the air guide pipe 11, the air hole 702, the through groove 6011, and the through hole 6012 in sequence. After being inflated, the sealed airbag cushion 6 will expand to a certain extent until the valve plate 5 is pressed on After the valve seat 4 is placed, the volume of the sealing airbag cushion 6 will also increase to a certain extent, so that the two sides of the sealing airbag cushion 6 can be closely attached to the valve plate 5 and the valve seat 4 respectively, which can effectively improve the sealing between the valve plate 5 and the valve seat 4 and the entire elastic sealing check valve 2, and combined with the extrusion force of the valve plate 5 on the valve seat 4, the sealing airbag cushion 6 can be more closely attached to the valve plate 5 and the valve seat 4, thereby further improving the sealing of the elastic sealing check valve 2 and preventing liquid backseepage caused by poor sealing;

[0064] Furthermore, the second corrugated section 1101 on the air guide tube 11 can ensure that the air guide tube 11 has a certain telescopic function, so that the air guide tube 11 can maintain communication with the air hole 702 on the slide seat 7 during the change of the distance between the slide seat 7 and the valve plate 5 .

[0065] Moreover, after the sealed airbag cushion 6 is inflated, its outer surface area will increase, and its outer surface tension will also increase. At this time, impurities adhering to the outer surface of the sealed airbag cushion 6 will also be loosened. In this case, the outer surface of the sealed airbag cushion 6 is flushed with water flow from the water hole 701, so that the loosened impurities can be flushed away and the elastic sealing check valve 2 can be flushed out, thereby achieving the purpose of automatically cleaning the magazines adhering to the sealed airbag cushion 6.

[0066] Embodiment 3

[0067] The present invention provides Figures 4 to 11 A low resistance backflow preventer is shown: a first groove 401 adapted to the sealing airbag cushion 6 is formed on a side of the valve seat 4 close to the valve plate 5, and a second groove 503 adapted to the sealing airbag cushion 6 is formed on a side of the valve plate 5 close to the valve seat 4, and an annular protrusion 15 is formed on the inner surfaces of the first groove 401 and the second groove 503.

[0068] The working principle is as follows: after the sealing airbag cushion 6 is inflated, its two sides will enter the first groove 401 and the second groove 503 respectively, and cling to the inner surfaces of the first groove 401 and the second groove 503 respectively. At the same time, the protrusions 15 in the first groove 401 and the second groove 503 will also squeeze the two side surfaces of the sealing airbag cushion 6, causing it to undergo a certain elastic deformation. Firstly, the squeezing action can increase the sealing contact area between the sealing airbag cushion 6 and the valve plate 5 and between the sealing airbag cushion 6 and the valve seat 4, thereby further improving the sealing performance of the elastic sealing check valve 2. In addition, the squeezing action can also increase the sealing contact area between the sealing airbag cushion 6 and the valve plate 5 and the sealing airbag cushion 6 and the valve seat 4. This operation can also increase the close contact between the sealing airbag cushion 6 and the valve plate 5 and the valve seat 4 respectively, thereby further improving the sealing performance, and through the arrangement of the first groove 401 and the second groove 503 of the squeezing action, the sealing airbag cushion 6 can be retracted into the first groove 401 and the second groove 503, so that the corresponding sides of the valve plate 5 and the valve seat 4 can also be closely attached together, thereby further improving the sealing performance. In summary, the arrangement of the first groove 401, the second groove 503 and the protrusion 15 can further improve the sealing performance of the elastic sealing check valve 2, thereby further improving the sealing performance of the entire backflow preventer.

[0069] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low resistance backflow preventer, comprising a main valve body (1), wherein two elastic sealing check valves (2) are arranged inside the main valve body (1), and a hydraulic differential drain valve (3) is arranged outside the main valve body (1), characterized in that: The elastic sealing check valve (2) comprises a valve seat (4) and a valve plate (5); the valve plate (5) is fixedly connected to the outside of the valve plate (5); the valve stem (501) is arranged on the valve seat (4); and a return spring (502) is arranged between the valve stem (501) and the valve seat (4); The outside of the valve stem (501) is sleeved and slidably connected with a sliding seat (7) between the valve seat (4) and the valve plate (5), the outside of the sliding seat (7) is sleeved with an annular sealing airbag cushion (6), a first spring (12) is provided between the sliding seat (7) and the valve plate (5), and a buffer component is provided between the sliding seat (7) and the valve seat (4); The valve plate (5) is provided with a water storage device (8) connected to the slide seat (7) on the outside, and a plurality of water guide pipes (10) are provided between the water storage device (8) and the slide seat (7). The outer surface of the slide seat (7) is provided with a plurality of water holes (701), and the water holes (701) are in communication with the water guide pipes (10); An air-filling device (9) connected to the water storage device (8) is provided outside the valve plate (5); an air-guiding tube (11) is provided between the air-filling device (9) and the slide seat (7); a mounting ring (601) is provided between the inner hole wall of the sealing airbag cushion (6) and the outer surface of the slide seat (7); and the sealing airbag cushion (6) is connected to the air-guiding tube (11) via the mounting ring (601) and the slide seat (7); A first groove (401) adapted to match the sealing airbag cushion (6) is formed on a side of the valve seat (4) close to the valve plate (5), and a second groove (503) adapted to match the sealing airbag cushion (6) is formed on a side of the valve plate (5) close to the valve seat (4), and inner surfaces of the first groove (401) and the second groove (503) are both provided with annular protrusions (15).

2. The low resistance backflow preventer according to claim 1, characterized in that: The buffer assembly comprises a pressure plate (13) and a second spring (14); the pressure plate (13) is slidably connected to the outside of the valve stem (501); and two ends of the second spring (14) are respectively connected to the pressure plate (13) and the sliding seat (7).

3. The low resistance backflow preventer according to claim 1, characterized in that: The water storage device (8) comprises a water storage cylinder (801), the interior of the water storage cylinder (801) is slidably connected to a first piston (802), the exterior of the first piston (802) is fixedly connected to a first piston rod (803), and the first piston rod (803) is connected to a sliding seat (7) by penetrating a valve plate (5).

4. The low resistance backflow preventer according to claim 1, characterized in that: The water conduit (10) is provided with a first corrugated section (1001) of which the length can be extended and retracted, and the first corrugated section (1001) is located between the valve plate (5) and the sliding seat (7).

5. The low resistance backflow preventer according to claim 1, characterized in that: The plurality of water holes (701) are divided into two water hole groups, the two water hole groups are respectively located on both sides of the sealed airbag cushion (6), and the plurality of water holes (701) in the two water hole groups are distributed divergently along the axis of the valve stem (501).

6. The low resistance backflow preventer according to claim 3, characterized in that: The inflation device (9) comprises an air cylinder (901) fixedly connected to the outer surface of the water storage device (8); a second piston (902) is slidably connected to the interior of the air cylinder (901); a second piston rod (903) is fixedly connected to the exterior of the second piston (902); and an end of the second piston (902) away from the second piston (902) is fixedly connected to the first piston (802) by being inserted into the water storage cylinder (801).

7. The low resistance backflow preventer according to claim 1, characterized in that: The outer surface of the sliding seat (7) is provided with an air hole (702), and the inner ring wall of the mounting ring (601) is provided with a circular through groove (6011), and the through groove (6011) is connected to the air guide pipe (11) through the air hole (702).

8. The low resistance backflow preventer according to claim 7, characterized in that: A through hole (6012) is provided inside the mounting ring (601), the inner ring wall of the sealed airbag cushion (6) is open, and the inner cavity of the airbag cushion (6) is connected to the air hole (702) through the inner ring wall opening and the through hole (6012).

9. The low resistance backflow preventer according to claim 1, characterized in that: The mounting ring (601) is fixed to the outside of the sliding seat (7) by means of screw sleeves, and a sealing ring (6013) is provided between the inner ring wall of the mounting ring (601) and the outer surface of the sliding seat (7).

10. The low resistance backflow preventer according to claim 1, characterized in that: The air guide pipe (11) is provided with a second corrugated section (1101), and the second corrugated section (1101) is located between the valve plate (5) and the sliding seat (7).

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