duckbill valve

Abstract

This invention provides a duckbill valve, comprising an installation section, a contraction section, and a sealing section. The sealing section has an outlet slit closed along an axis by two sealing surfaces. The outlet slit has at least a portion of different lengths along the axial direction from the upper edge of the sealing surface to the lower edge of the sealing surface, with the length of the lower edge of the sealing surface being less than the length of the upper edge of the sealing surface. This duckbill valve employs a widened sealing surface design on both sides of the outlet slit. At the end of the drainage process, the path of water containing solid impurities through the outlet slit is shortened, thus reducing the deposition of solid impurities in the water at the lower part of the outlet slit, thereby ensuring effective sealing of the duckbill valve after drainage.

Description

Technical Field

[0001] This invention relates to the field of one-way check valve technology for water conservancy facilities, specifically to a duckbill valve. Background Technology

[0002] The use of duckbill valves to prevent sewage backflow at drainage outlets is a common technical method in urban sewage pipe network design. A typical duckbill valve has a flat outlet slit made of flexible elastic material. When there is no internal flow in the pipe, external pressure or self-closing causes the lip of the outlet to close the valve. The flexible elastic component of existing duckbill valves is generally made of composite material with a rubber body and reinforcing layers. Duckbill valves require no power and utilize the pressure difference between the inside and outside of the valve or self-closing to prevent backflow, as well as the low water pressure required for forward opening. They are particularly suitable for sewage pipe network facilities in harsh environments that require long-term reliable operation.

[0003] A utility model patent with publication number CN201145067Y entitled "Duckbill Check Valve" has disclosed such a duckbill valve for preventing backflow of drainage. The reverse seal of the valve is maintained by the reverse pressure of the medium on the lip of the duckbill valve on the outlet side, and the installation and fixing of the valve inlet side is reinforced with metal material in order to obtain higher connection strength.

[0004] In addition, a utility model patent entitled "Duckbill Check Valve" with publication number CN204852496U discloses a duckbill valve with magnetic strips on both sides of the sealing surface, which prevents the check valve from not closing tightly by the mutual attraction of the magnets.

[0005] Due to the unique nature of sewage pipe networks, even after interception by facilities such as screens, solid impurities inevitably remain in the flowing water. Duckbill valves are typically installed vertically or nearly vertically at the pipe outlet with an outlet slit. As the flow rate decreases in the pipe, the water level gradually drops, the head pressure decreases, and the outlet slit of the duckbill valve gradually closes. During this process, the outflow concentrates at the lower part of the outlet slit. Towards the end of the drainage process, because the flow rate is already very low and the flow velocity is very slow, and the outlet slit is nearly closed with a small cross-section, coupled with the reduced flow velocity leading to near-laminar flow, denser solid impurities gradually accumulate at the bottom of the pipe. The combined effect of these factors results in solid impurities depositing and clogging the lower part of the outlet slit of the duckbill valve towards the end of the drainage process. This prevents the duckbill valve from effectively sealing and thus cannot effectively prevent backflow. In other words, existing technologies cannot solve the most important function of duckbill valves—preventing backflow due to debris. Summary of the Invention

[0006] To address the problem that existing duckbill valves are prone to clogging the outflow slot and thus cannot effectively prevent backflow, this invention provides a duckbill valve.

[0007] The present invention provides a duckbill valve, which includes an installation section, a contraction section and a sealing section. The sealing section has an outflow slit closed along the axis by two sealing surfaces. The outflow slit has at least a portion of different lengths along the axial direction from the upper edge of the sealing surface to the lower edge of the sealing surface, and the length of the lower edge of the sealing surface is less than the length of the upper edge of the sealing surface.

[0008] Preferably, the length of the lower edge of the sealing surface is 2 to 400 mm.

[0009] Preferably, the ratio of the length of the lower edge of the sealing surface to the thickness of the sealing surface at the lower edge of the sealing surface is in the range of (0.5 to 20):1.

[0010] Preferably, the ratio of the length of the lower edge of the sealing surface to the thickness of the sealing surface at the lower edge of the sealing surface is in the range of (10~15):1.

[0011] Preferably, the outlet curve of the sealing section is distributed in a stepped manner, and the relationship between the height h of the lower edge of the sealing surface and the total height H of the outflow slit is: h≤1 / 4H.

[0012] Preferably, the outlet curve includes at least an inclined straight line extending from the lower edge of the sealing surface.

[0013] Specifically, the outlet curve is an inclined straight line connecting the lower edge of the sealing surface to the upper edge of the sealing surface.

[0014] Preferably, the outlet curve is a first-order continuous curve, and both ends of the outlet curve are perpendicular to the axis.

[0015] Specifically, the export curve is a sine curve.

[0016] Preferably, the sealing section forms an arc-shaped bend along the axial direction, and the angle α between the outflow direction and the inflow direction of the sealing section is 90 to 180 degrees.

[0017] Specifically, the sealing section is curved in an arc shape, and the ratio of the arc radius R to the length M of the upper edge of the sealing surface is in the range of (0.3 to 0.7):1.

[0018] To ensure the valve's sealing capability while reducing the possibility of solid impurities clogging the outlet slit and effectively preventing backflow, the duckbill valve of this invention features a widened sealing surface on both sides of the outlet slit. The width of the sealing surface increases from bottom to top, and the length of the outlet slit at the bottom is shorter. This means that at the end of the drainage process, the path of the water containing solid impurities through the outlet slit is shortened, thus reducing the deposition of solid impurities in the water at the bottom of the outlet slit and ensuring an effective seal of the duckbill valve after drainage.

[0019] The sealing surface of this invention is widened, with a smaller sealing surface width at the lower part compared to the upper part. Compared to existing duckbill valves with equal width, it can be understood that the lower sealing surface, due to the less material, has lower resistance to elastic deformation. Therefore, under the same lower incoming flow pressure, the duckbill valve of this invention is easier to open, thereby initiating drainage. In other words, the duckbill valve of this invention has a lower forward opening pressure compared to existing technologies.

[0020] The above considers the opening process of the duckbill valve. If we consider the closing process, since the width of the sealing surface decreases from top to bottom, its elastic contraction capacity also decreases from top to bottom. During the closing process as the incoming flow gradually decreases, the upper part of the sealing surface is relatively wider, thus achieving contact earlier. In other words, during the closing process of the duckbill valve, due to the gradient distribution of the elastic contraction capacity of the sealing surface, the outflow slit generally undergoes a dynamic process of active, downward extension of the sealing section. Because this process is dynamically and orderly expanded, it better ensures reliable sealing of the sealing surface, avoiding the sealing surface wrinkling and wavy opening seal failure that often occurs in existing technologies due to the large size of duckbill valves. On the other hand, when the width of the sealing surface at the upper end of the sealing surface of the opening part of the outlet slit is equal, compared with the duckbill valve where the sealing surface is of equal width from top to bottom, the sealing surface of the upper part of the opening part of the outlet slit will close earlier. In other words, it can better slow down the drop in water head pressure, thereby making the water flow rate relatively faster, and thus better preventing the duckbill valve from failing to close due to the deposition of solid impurities. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of Embodiment 1 of the duckbill valve of the present invention;

[0022] Figure 2 This is a schematic diagram of the AA cross-section of the sealing section of the present invention;

[0023] Figure 3 This is a schematic diagram of Embodiment 2 of the duckbill valve of the present invention;

[0024] Figure 4 This is a schematic diagram of Embodiment 3 of the duckbill valve of the present invention;

[0025] Figure 5 This is a schematic diagram of Embodiment 4 of the duckbill valve of the present invention;

[0026] Figure 6 This is a schematic diagram of the expansion of the sealing section in Embodiment 4 of the present invention;

[0027] Figure 7 This is a schematic diagram of Embodiment 5 of the duckbill valve of the present invention;

[0028] Figure 8 This is a top view schematic diagram of Embodiment 5 of the duckbill valve of the present invention.

[0029] In the picture,

[0030] 1: Duckbill valve 11: Sealing section 111: Sealing surface 111B: Lower edge of sealing surface 111T: Upper edge of sealing surface 11A: Outflow slot 11B: Outflow curve 11C: Upstream of sealing section 12: Contraction section 13: Installation section O: Axis UP: Vertical upward direction F1: Inflow direction F2: Outflow direction Detailed Implementation

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. In this specification, the dimensions of the drawings do not represent the actual dimensions. They are only used to illustrate the relative positional and connection relationships between the components. Components with the same name or the same reference numeral represent similar or identical structures and are limited to illustrative purposes.

[0032] Figure 1 This is a schematic diagram of Embodiment 1 of the duckbill valve of the present invention, for comparison. Figure 1 The part shown by the thin dashed line is the part that is extra in the duckbill valve of the prior art compared with the duckbill valve of the present invention. Of course, this is just a comparative illustration.

[0033] The duckbill valve 1 is generally integrally formed from a flexible elastic material, but this does not affect our functional division into three parts along its axis O: a sealing section 11, a contraction section 12, and an installation section 13. These three parts together constitute a channel for controlling the outflow. The installation section 13 is used for installation and fixation in the outlet pipe hole; the specific installation method is not within the scope of this invention. In the prior art, the installation section 13 may have a flexible or metal flange at its end for flange-fastened connection to the pipe hole. The installation section 13 can also be fitted onto the pipe, in which case it may be adaptively provided with a groove or flange for a limiting and fixing device. Figure 2 for Figure 1 The cross-sectional view of the middle sealing section 11 along the AA direction should be emphasized. Figure 2 This is a schematic diagram of the duckbill valve 1 in its normally closed state. In this state, the sealing section 11 consists of two mutually fitting sealing surfaces 111, which define the... Figure 2 The narrow outflow slit 11A in the middle is adapted to the check function of the duckbill valve 1. In the normally closed state, because the sealing surfaces 111 are in close contact, the cross-section of the outflow slit 11A degenerates into a single line segment, and there is no outflow space. Therefore, it can be understood that... Figure 2 In this diagram, the outflow slit 11A is drawn as a narrow slit only to illustrate the outflow channel, rather than as an actual closed state.

[0034] The contraction section 12 merely connects the mounting section 13 and the contraction section 12, and deforms along with the sealing section 11 when the sealing section 11 deforms. When the incoming flow causes the sealing section 11 to expand, the sealing section 11 moves circumferentially along the axis O. In actual installation of the duckbill valve 1, the outlet slit 11A is usually set in a vertical plane rather than horizontally, that is... Figure 2 The direction UP shown is vertically upward, primarily to prevent water accumulation inside the pipe and reduce the deposition of solid impurities. From Figure 1 As can be seen, when the outlet slit 11A is vertically installed, its lowest point is lower than the installation section 13, or the lowest point of the incoming pipe, thus preventing water accumulation inside the pipe. However, when installed horizontally, the outlet slit 11A is roughly located at the axial height of the installation section 13. Nearly half of the pipe's cross-section is blocked by the lower half of the contraction section 12, preventing drainage and causing water accumulation and solid impurity deposition. Furthermore, under long-term water accumulation, the lower half of the contraction section 12 will deform due to internal water pressure, ultimately affecting the sealing of the sealing section 11.

[0035] Although this application specifies that the outflow slot 11A should be set in the vertically upward direction (UP), a certain range of human deviation is permissible even without considering installation tolerances. If the outflow slot 11A must be set at an angle to the vertical plane, it is recommended that the lowest point of the outflow slot 11A in the normally closed state be below the zero-height water level line of the pipe outlet, or, under certain installation methods, can be understood as the height of the lowest point of the inner wall of the pipe. Furthermore, when the sealing section 11 is fully expanded, it is recommended that the outflow cross-section should not be less than the outflow cross-section of the installation section 13; that is, the full circumference of the sealing section 11 formed by the sealing surface 111 around the axis O should not be less than the full circumference of the installation section 13, to ensure the outflow area under extreme conditions. The vertically upward direction (UP) in the following description is merely for illustrative purposes and does not imply that the technical solution of this invention cannot be set at an angle to the vertical direction. Based on this, this application defines the lower edge 111B and the upper edge 111T of the sealing surface, where the lower edge 111B and the upper edge 111T of the sealing surface correspond to the lower edge and the upper edge of the sealing surface 111 in the aforementioned installation state, respectively.

[0036] To mitigate the deposition of solid impurities at the lower part of the outflow slit 11A, a possible solution is to reduce the outflow length at the lower part of the outflow slit 11A, which corresponds to the length of the lower edge of the sealing surface 111B along the axis O. To ensure the overall sealing and backflow prevention function of the sealing section 11, the minimum length m of the lower edge of the sealing surface 111B should not be less than 2 mm, depending on the size of the duckbill valve. To ensure a suitable positive opening pressure, the minimum sealing length of the outflow slit 11A, i.e., the length of the lower edge of the sealing surface 111B, should not be too large, with a maximum value of 400 mm. Based on this, to achieve a match between the elastic properties and sealing performance of the sealing surface 111, the ratio of the length of the lower edge of the sealing surface 111B to the thickness of the sealing surface 111 at the lower edge of the sealing surface 111B is (0.5~20):1. A preferred range is (10~15):1. When the thickness of the sealing surface 111 at the lower edge of the sealing surface 111B is not uniformly distributed, the thickness in the above ratio can refer to the average thickness.

[0037] Specifically, a duckbill valve can be like Figure 1 As shown, the lower edge 111B of the sealing surface is partially cut off along the direction of axis O. Figure 1 For a uniform width cut-off method, a stepped outlet curve 11B is formed on the sealing section 11. To balance the sealing performance of the sealing section 11, its original width should be retained within a relatively large range. Therefore, the height h of the lower edge 111B of the sealing surface should not exceed half the total length H of the outflow slit 11A. A more preferred option is h ≤ 0.25H. The retained length of the lower edge 111B of the sealing surface is m. To reduce the deposition of solid impurities in the outflow slit 11A, the length m of the lower edge 111B of the sealing surface should be shortened as much as possible to reduce the flow distance of wastewater containing impurities in the outflow slit 11A, thereby reducing deposition. It also reduces the resistance of the sealing section 11 to the incoming flow, making the flow smoother and further reducing deposition. However, the lower edge 111B of the sealing surface cannot be shortened indefinitely; it must maintain an appropriate length to perform its normal sealing and backflow prevention function. The above ratio is not fixed for products of different sizes. Generally, the larger the product size, the smaller the above ratio is. The size information of some of the above-mentioned designs in the applicant's product series listed in the table below can illustrate this situation.

[0038] exist Figure 1 Based on the implementation method, the duckbill valve can also be used as follows: Figure 3 The setup is shown in Example 2. Figure 3 This is a cross-sectional view of Embodiment 2. Embodiment 2 removes the cut portion of the lower edge 111B of the sealing surface by beveling. Other dimensional requirements remain the same as in Embodiment 1. For those skilled in the art, methods for setting an appropriate length for the lower edge 111B of the sealing surface include, but are not limited to, Embodiments 1 and 2 already provided in this application; the cut portion can be reasonably planned as needed.

[0039]

[0040] Dimensional design of different models of duckbill valves (unit: mm)

[0041] The shape is adjusted to obtain an appropriate length for the lower edge 111B of the sealing surface. It should also be noted that the cut-out portion referred to in the above embodiments specifically refers to the portion missing from the lower edge 111B of the sealing surface on the sealing segment 11 compared to the upper edge 111T of the sealing surface; however, this does not require that the missing portion be formed solely by cutting away material as literally indicated. This invention does not specify the specific forming process of the cut-out portion; those skilled in the art can determine, based on specific production processes, that the cut-out portion is formed by additive manufacturing, subtractive manufacturing, or a mold of a specific shape.

[0042] The main purpose of the specific implementation methods described in Examples 1 and 2 is to shorten the length of the lower edge 111B of the sealing surface in order to effectively reduce the deposition of solid impurities and prevent clogging. Since the modification is mainly concentrated at the lower edge 111B of the sealing surface, the overall change to the sealing section 11 is minimal, and therefore the overall operation of the sealing section 11 is not significantly affected. The forward opening pressure of the sealing section 11 is slightly reduced due to the shortening of the lower edge 111B of the sealing surface, but the reduction is not significant. The main body of the sealing surface 111 remains at the same width and length as the upper edge 111T of the sealing surface.

[0043] In this regard, this application also provides, for example Figure 4 Example 3 is shown. In the figure, under the tight sealing state, the outlet curve 11B is a sloping straight line from bottom to top, thereby continuously expanding the flow width of the sealing section 11 from bottom to top. This ensures the sealing area and length of the sealing section 11 as a whole, thus having a reverse check valve performance that is basically equivalent to that of a duckbill valve with a normal equal-width sealing section. At the same time, when the water level drops at the end of the outflow, the upper expansion section gradually closes, and the outflow mainly flows out from the lower part of the shorter width of the outflow slit 11A. Because the flow distance of the outflow slit 11A is short, on the one hand, the path of the incoming flow through the lower part of the outflow slit 11A is reduced, reducing the possibility of solid impurities being deposited in the outflow slit 11A. On the other hand, because the width of the sealing surface 111 is short, its elasticity is weak, and its obstruction effect on the incoming flow is smaller. Even if there are solid impurities such as mud and sand in the incoming flow, they can be smoothly flushed out of the outflow slit 11A with less obstruction.

[0044] As the outlet slit 11A gradually closes from the open state, the incoming water level gradually decreases. The outlet slit 11A inevitably undergoes a process of its sealing surface gradually extending downwards from top to bottom. In this embodiment, the sealing surface 111 is widened, and its elastic closing ability gradually decreases from top to bottom. Therefore, during the downward extension of the sealing surface's contact section, the part that is to be contacted has a larger width than the lower, uncontacted part, making the contact process easier to occur. Thus, the duckbill valve 1 of the present invention can avoid the problem of the original sealing surface 111 of equal width, where the elasticity of each part is basically the same, resulting in the inability to strictly extend from top to bottom during the contact process, thereby causing wrinkles and affecting the seal.

[0045] The above embodiment is not the preferred embodiment of this application because the outlet curve 11B, which is set in a straight line, does not have a first-order continuous joint between the sealing surfaces 111 on both sides of the upper and lower parts of the sealing section 11 after expansion. This is not conducive to increasing the opening and closing frequency of the sealing section 11 and extending its fatigue life. Moreover, under actual incoming flow conditions, the outflow slot 11A is always opened first from the sealing section 11 and gradually expands upward, rather than acting simultaneously on the entire outflow slot 11A.

[0046] Therefore, this application also provides, for example Figure 5 Example 4 is shown. Its outlet curve 11B is a continuous curve of at least one order, and its tangential direction at the upper and lower parts of the sealing section 11 is perpendicular to the axis O. Therefore, the outlet curve 11B can ensure that the upper and lower joints of the sealing surface 111 are always tangent during the process of the outflow slit 11A from closing to expanding, and there will be no possible circumferential bends at both ends when the straight line is set.

[0047] Preferably, in the above embodiment 4, the outlet curve 11B is a sine curve, such as... Figure 6 As shown, when the outflow slot 11A fully expands into a circular outflow cross section, the outlet curve 11B is in the same plane and forms an elliptical cross section. From the side, the outlet of the sealing section 11 is a straight line, which is beneficial to the uniform stress on the sealing section 11 under the maximum outflow state and avoids damage to the weak points of the sealing surface 111 under turbulent impact.

[0048] This application also provides, for example Figure 7 Example 5 is shown. The sealing section 11 of the treated duckbill valve 1 is bent into an arc shape along the direction of axis O to improve the elastic recovery sealing ability of the sealing surface 111 and the reliability under sealing conditions. Figure 8 for Figure 7 A schematic cross-sectional view of an embodiment along the vertically upward direction (UP). Figure 7This diagram only illustrates the shape of the sealed section 11 when closed. For those skilled in the art, the outlet slit 11A is perfectly closed; the width shown is for illustrative purposes only and does not represent the actual situation. Since this is a schematic diagram along the vertical upward direction (UP), and the length of the sealed section 11 along axis O varies, the outlet curve 11B in the diagram is actually the position of the longest outlet curve 11B of the sealed section 11, i.e., at the upper edge 111T of the sealing surface. The upstream of the sealed section 11C is... Figure 6 In the section connected to the contraction section 12, the incoming flow direction F1 remains along the axis O. After bending, the angle between the outflow direction F2 and the incoming flow direction F1 at the sealing section 11 is α, with α preferably ranging from 90 to 180 degrees. Figure 7 As can be seen, although the sealing surface is bent by an angle α along its entire length, the length of the sealing surface 111 along the axis O is shortened from top to bottom. Therefore, at the lower edge 111B of the sealing surface, its length is shorter, and the bending angle is correspondingly reduced. Furthermore, due to the overall curvature of the sealing section 11, wrinkles on the sealing surface 111 in the closed state can be avoided, effectively maintaining its shape and sealing performance. Normally, a bent sealing section 11 would increase resistance to the incoming flow, leading to a higher forward opening pressure. However, in the technical solution of this application, the variable-length sealing surface 111 can better avoid this problem. Since the length of the sealing surface 111 shortens from top to bottom, the bending has a greater impact on the opening pressure at the upper part of the sealing section 11. At the lower part, due to its shorter length, under the same bending conditions, it can only complete a partial bend relative to the upper edge 111T of the sealing surface, with a smaller bending angle. Therefore, it has less resistance to the incoming flow and less impact on the forward opening pressure. By rationally setting the relationship between the starting point of the bend in the sealing surface 111 and the length of the lower edge 111B of the sealing surface, the opening pressure of the sealing section can be effectively controlled to prevent significant changes. In a preferred embodiment, the sealing section 11 is curved in an arc shape, or at least partially curved, to facilitate processing and achieve the lowest flow resistance at the same bending angle. To ensure that the upper edge 111T of the sealing surface achieves the required bending angle under the arc-curved design, the arc radius R is preferably controlled within the range of 0.3 to 0.7 times the length M of the upper edge 111T of the sealing surface.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A duckbill valve, comprising an installation section (13), a contraction section (12), and a sealing section (11), characterized in that, The sealing section (11) has an outflow slit (11A) closed along the axis (O) by two sealing surfaces (111); the outflow slit (11A) has at least a partial length along the axis (O) from the upper edge (111T) of the sealing surface to the lower edge (111B) of the sealing surface, and the length of the lower edge (111B) of the sealing surface is less than the length of the upper edge (111T) of the sealing surface; the ratio of the length of the lower edge (111B) of the sealing surface to the thickness of the sealing surface (111) at the lower edge (111B) of the sealing surface is in the range of (2-4):1; the length of the lower edge (111B) of the sealing surface is 2-400mm; the outlet curve (11B) of the sealing section is a first-order continuous curve, and both ends of the outlet curve (11B) are perpendicular to the axis. (O) Vertical; The outlet curve (11B) is a sine curve; The sealing section (11) forms an arc bend along the direction of the axis (O), the incoming flow direction (F1) is along the axis (O), and the angle α between the outflow direction (F2) and the incoming flow direction (F1) of the sealing section (11) is 90 to 180 degrees; The sealing section (11) is curved in an arc shape, and the ratio of the arc radius R to the length M of the upper edge (111T) of the sealing surface is (0.3 to 0.7):1; The sealing section (11) is bent by α degrees along the entire length of the upper edge (111T) of the sealing surface, and the length of the sealing surface (111) along the axis (O) is shortened from top to bottom. At the lower edge (111B) of the sealing surface, the length is short and the angle of bending is reduced.

Images