House building roof drainage structure and construction method thereof

Abstract

This application relates to a roof drainage structure and its construction method, belonging to the field of building roof drainage technology. It includes a drainage hopper, a drainage pipe located below the drainage hopper, a vortex-blocking plate located above the drainage hopper inlet, and a cantilever rod extending downwards from the center of the vortex-blocking plate. An annular inlet gap is formed between the outer edge of the drainage hopper inlet and the bottom surface of the vortex-blocking plate. The upper inner wall of the drainage pipe is provided with an elastic variable-diameter throat with an annular cavity, connected to the downstream negative pressure zone via a pressure-guiding pipe. An air intake channel runs through the vortex-blocking plate and the cantilever rod, with its upper end connected to the atmosphere and equipped with an air intake valve, and its lower end connected to a Venturi nozzle. The nozzle's jet orifice is obliquely oriented towards the annular inlet gap. Under normal siphon negative pressure, this application can extract air from the cavity to drive the elastic variable-diameter throat to retract, increasing the flow area. When flexible debris is blocked, the ultimate negative pressure triggers a high-speed jet to blow away the blockage, improving the continuity, stability, and anti-clogging ability of roof drainage, and reducing the impact of negative pressure overload suction.

Description

Technical Field

[0001] This application relates to the technical field of building roof drainage, and in particular to a roof drainage structure for buildings and its construction method. Background Technology

[0002] Existing roof drainage systems typically use drainage hoppers to collect rainwater into drainage pipes. In some projects, flow guiding, flow blocking, or air-injection components are also used to improve water intake organization and drainage efficiency. When using a full-pipe siphon method, the downstream negative pressure can significantly improve drainage capacity. This is a common and effective technical approach for high-flow-rate roof drainage.

[0003] However, rooftop environments often contain flexible debris such as thin films, lint, and lightweight silt, which easily adhere to and block the inlet of the drain hopper. Because the water inlet conditions change abruptly after blockage, the negative pressure inside the drain pipe will further increase. If only a fixed flow channel or conventional air supply structure is used, on the one hand, a low opening threshold will allow air to enter prematurely, weakening the full-pipe siphon and reducing effective flow capacity; on the other hand, a high opening threshold will prevent timely pressure relief and clearing under extreme blockage conditions, and local components will be subjected to continuous overload suction and pulsating impacts. Furthermore, if the pressure tapping location is affected by flow field scouring or debris interference, the negative pressure signal will deviate, leading to unstable operation, frequent maintenance, and an increased risk of roof water accumulation.

[0004] Therefore, roof drainage needs to simultaneously consider the stability of full-pipe siphon, the ability to automatically clear obstacles when blocked by flexible debris, and overload protection for key components. Summary of the Invention

[0005] To address the challenges of balancing flow capacity, resistance to malfunctions, and automatic obstacle removal in roof drainage systems subjected to full-pipe siphoning and flexible debris blockage, this application provides a roof drainage structure and its construction method.

[0006] This application provides a roof drainage structure and its construction method for residential buildings, which adopts the following technical solution: The first aspect of this application provides a roof drainage structure for residential buildings, which adopts the following technical solution: A roof drainage structure for a building includes a drainage hopper and a drainage pipe disposed below the drainage hopper, and further includes: The flow guiding component includes a vortex-blocking plate disposed above the inlet of the drainage bucket and a cantilever rod extending downward from the center of the vortex-blocking plate, with an annular inlet gap formed between the outer edge of the inlet of the drainage bucket and the bottom surface of the vortex-blocking plate. A reducing assembly includes an annular elastic reducing throat disposed on the inner wall of the upper end of the drain pipe, the elastic reducing throat having an annular cavity and the annular cavity being connected to the downstream negative pressure zone of the drain pipe via a pressure guiding pipe; and The jet clearing assembly includes an air intake channel that runs longitudinally through the vortex baffle and the cantilever rod. The top of the air intake channel is connected to the atmosphere and an air inlet valve is provided on the top of the vortex baffle. The bottom of the air intake channel is connected to a Venturi nozzle located at the end of the cantilever rod. The jet orifice of the Venturi nozzle is located on its side wall and is obliquely directed toward the annular water inlet gap. In the case of full-pipe drainage, the normal siphon negative pressure generated in the negative pressure zone downstream of the drainage pipe draws gas from the annular cavity through the pressure guide pipe, causing the elastic variable-diameter throat to contract towards the inner wall of the drainage pipe to increase the drainage flow area; in the case of extreme negative pressure where the annular water inlet gap is blocked by flexible debris, the transient extreme negative pressure in the drainage pipe overcomes the set resistance and draws open the air inlet valve, and the external air is accelerated at the Venturi nozzle through the air duct to form a high-speed jet that blows off the blockage at the annular water inlet gap.

[0007] Furthermore, the intake valve includes a valve housing with one end connected to the atmosphere, a normally closed valve core that is slidably sealed to the fluid passage inside the valve housing, and a pre-tightening locking assembly disposed between the valve housing and the normally closed valve core. The pre-tightening locking assembly includes a return spring that presses against the valve body and the normally closed valve core, and a magnetic attraction mechanism. The sum of the closing force of the return spring and the static magnetic attraction force of the magnetic attraction mechanism constitutes an opening yield resistance threshold. The absolute value of the opening yield resistance threshold is greater than the absolute value of the normal siphon negative pressure of the drainage pipe under full pipe drainage conditions, and less than the absolute value of the ultimate tensile pressure of the elastic variable diameter throat when it undergoes irreversible tensile failure.

[0008] Furthermore, the magnetic attraction mechanism includes a static magnetic component fixedly installed on the top of the valve housing and a moving magnetic component fixed on the top of the normally closed valve core, the two being magnetically attracted to each other; When the annular inlet gap does not reach the limit negative pressure state, the moving magnetic component and the stationary magnetic component attract each other to limit the micro-leaking of the normally closed valve core under normal siphon negative pressure; When the negative pressure in the drain pipe reaches the transient extreme negative pressure, the normally closed valve core is subjected to downward fluid pressure difference suction force to overcome the opening yield resistance threshold. The moving magnetic component instantly detaches from the stationary magnetic component. The static magnetic attraction force decreases sharply as the separation distance of the magnetic components increases, so that the normally closed valve core instantly overcomes the elastic force of the return spring to reach the maximum opening degree, causing the air passage to be fully opened to form an explosive high-speed jet.

[0009] Furthermore, while the air intake channel is opened and airflow is introduced at high speed, the introduced external air releases the transient extreme negative pressure in the drain pipe, drives the normally closed valve core to reset and close under the action of the pre-tightening locking assembly, and releases the transient overload suction on the elastic variable diameter throat. The jet orifice axis of the Venturi nozzle forms a grazing angle of 5°-15° with the virtual plane containing the annular water inlet gap.

[0010] Furthermore, the sidewall of the Venturi nozzle is covered with a resilient duckbill valve around its jet orifice; When the pipe is fully drained, the water pressure in the drain hopper causes the slit of the elastic duckbill valve lip to close, preventing external mud and sand from flowing back into the air intake channel. Under extreme negative pressure, the high-speed airflow in the air intake duct forces open the elastic duckbill valve and is squeezed by the lip of the elastic duckbill valve to form a flat jet air knife.

[0011] Furthermore, in the initial state without negative pressure suction, the elastic variable diameter throat has a funnel shape with a gradually narrowing cross section from top to bottom, and the wall thickness of the elastic variable diameter throat gradually decreases from top to bottom.

[0012] Furthermore, the pressure guiding tube is a capillary tube with an inner diameter of less than 2 mm. The inner diameter flow resistance parameter of the pressure guiding tube is matched with the volume of the annular cavity of the elastic variable diameter throat, so that the gas filling and releasing rate in the annular cavity is less than the short-term negative pressure change rate caused by the water flow pulsation in the drain pipe. This ensures that the contraction and reset action of the elastic variable diameter throat is not disturbed by short-term hydraulic fluctuations and has damping delay characteristics.

[0013] Furthermore, the pressure-conducting pipe is connected to the end of the negative pressure zone downstream of the drain pipe and is provided with a pressure tapping head. The pressure tapping head has a pressure tapping hole on the back flow surface of the water flow, and the pressure tapping head is covered with a static pressure shield with one end open downwards, so as to use the ejection effect generated by the water flow passing through the static pressure shield to extract impurities and extract stable static pressure.

[0014] Furthermore, the pressure tapping head is fixed with a plurality of arc-shaped spring pieces that are evenly distributed around the circumference and extend radially outward. The arc-shaped spring pieces are deformed under pressure and abut against the inner wall of the drain pipe, so as to suspend and anchor the pressure tapping head and the static pressure shield in the center region of the flow field of the drain pipe, thereby preventing the pressure guide pipe from undergoing vibration fatigue and pressure tapping point displacement under the scouring of the high-speed siphon full pipe water flow.

[0015] The second aspect of this application provides a construction method for roof drainage in building structures, which adopts the following technical solution: A method for constructing a roof drainage system for a building, based on the aforementioned roof drainage structure, includes the following steps: S1. Structural positioning and arrangement: Fix the drainage hopper to the roof gutter or the low-lying area of ​​the catchment area, and connect it vertically downward to the drainage pipe; insert the pressure guide pipe into the drainage pipe through the drainage hopper, and extend the pressure tap at the end of the pressure guide pipe downward to the point of maximum negative pressure of the fluid at a vertical distance of more than 3 meters from the drainage hopper. S2. Jet orientation configuration: When assembling the flow guide assembly, adjust the circumferential installation angle of the cantilever rod according to the direction of the gutter, so that the center of the jet hole of the Venturi nozzle at the end of the cantilever rod is aligned with the area of ​​the annular water inlet gap that is most susceptible to wind-driven film or fluff accumulation. S3. Physical calibration of anti-interference threshold: Obtain the design full-pipe siphon head height difference from the building roof to the ground, and calculate the peak value of normal siphon negative pressure in the drainage pipe accordingly; by adjusting the initial force parameters of the pre-tightening locking component in the air inlet valve, ensure that the absolute value of the opening yield resistance threshold of the air inlet valve is strictly between the absolute value of the peak value of normal siphon negative pressure and the absolute value of the tensile failure of the elastic variable diameter throat.

[0016] In summary, the beneficial technical effects of this application are as follows: 1. By setting a pre-tightening locking type intake valve composed of a return spring and a magnetic attraction mechanism, and combining its opening yield resistance threshold with the tensile threshold of the elastic variable diameter throat, the normally closed valve core is locked by both magnetic force and elastic force under normal siphon negative pressure to achieve zero leakage, while it instantly trips and fully opens under extreme negative pressure. This achieves a purely mechanical nonlinear pulse opening characteristic, effectively solving the problem of slow leakage at the critical point of conventional linear valves leading to siphon failure and insufficient jet kinetic energy. At the same time, it takes into account the high efficiency of normal siphon and the explosive force for breaking and clearing obstacles under extreme working conditions. 2. By utilizing the transient extreme negative pressure generated by the blockage of the siphon system itself as the sole power source for opening the intake valve and clearing the obstruction with the jet, and by splitting and time-division multiplexing the energy of this extreme negative pressure, that is, at the instant the transient extreme negative pressure is generated, the jet component is driven to complete the obstruction clearing action, and the flexible variable diameter throat is protected by venting and depressurizing, thus forming a pure fluid physical closed loop that does not require external energy, sensors or controllers, effectively solving the problems of slow response, system complexity and poor reliability of traditional electronic control schemes; 3. By designing a capillary pressure-conducting tube with an inner diameter of less than 2 mm and matching its flow resistance parameters with the volume of the annular cavity of the elastic variable diameter throat, the inflation and deflation rate of the elastic variable diameter throat is lower than the short-term negative pressure change rate caused by water flow pulsation. This gives the variable diameter component a damping delay characteristic, enabling it to automatically filter out interference such as high-frequency water flow pulsation and turbulence, and only respond to long-term stable siphon negative pressure signals, effectively improving the system's operational stability and anti-interference ability under complex flow conditions. 4. By combining capillary pressure guide tubes, backflow surface pressure taps, static pressure shields, and bow-shaped springs, the downstream negative pressure extraction is more stable and the pressure tapping point is less prone to deviation, thereby achieving effective tracking of full-pipe siphon pulsation and improving the problems of pressure guide tube vibration fatigue and negative pressure control inaccuracy under high-speed water flow scouring. 5. By adding an elastic duckbill valve to the outside of the venturi nozzle jet orifice, the lip of the valve closes under hydrostatic pressure to prevent clogging and opens under dynamic pressure to shape the tubular airflow into a flat jet air knife. This ingeniously integrates the requirements for preventing backflow of mud and sand under hydrostatic pressure and the requirements for efficient obstacle removal under extreme negative pressure into one component. This effectively solves the dilemma of easy clogging of the jet orifice and insufficient obstacle removal energy density, and significantly improves the long-term maintenance-free nature and adaptability to harsh working conditions of the structure. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application; Figure 2 This is a cross-sectional structural diagram of an embodiment of this application; Figure 3 This is a partial cross-sectional structural diagram of an embodiment of this application; Figure 4 This is a cross-sectional view of the intake valve in an embodiment of this application; a is the full pipe drainage state, and b is the ultimate negative pressure state; Figure 5 This is a schematic diagram of the structure of the flow guiding component and the jet obstacle clearing component according to an embodiment of this application; Figure 6 This is a schematic diagram of the structure of the variable diameter component according to an embodiment of this application.

[0018] Explanation of reference numerals in the attached figures: 11. Drain hopper; 12. Drain pipe; 121. Downstream negative pressure zone; 13. Gutter; 21. Vortex baffle; 22. Cantilever rod; 221. Air intake duct; 23. Annular water inlet gap; 3. Flexible reducing throat; 31. Annular cavity; 32. Pressure guiding tube; 4. Intake valve; 41. Valve body; 411. Conical sealing surface; 412. Support; 4121. Central through hole; 413. Positioning wing; 42. Normally closed valve core; 421. Sealing conical surface; 43. Return spring; 44. Static magnetic component; 45. Moving magnetic component; 5. Venturi nozzle; 51. Flexible duckbill valve; 61. Pressure tap; 62. Static pressure shield; 63. Bow-shaped spring. Detailed Implementation

[0019] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] This application discloses a roof drainage structure for buildings. (Refer to...) Figures 1-6 It includes a drainage hopper and a drainage pipe located below the drainage hopper, as well as a flow guiding component, a diameter reducing component and a jet clearing component. The drainage hopper is installed on the drainage path of the gutter.

[0021] Among them, reference Figure 2 , Figure 3 and Figure 5 The flow guiding component includes a vortex-blocking disc positioned above the inlet of the drainage hopper and a cantilever rod extending downwards from the center of the vortex-blocking disc. An annular inlet gap is formed between the outer edge of the drainage hopper's inlet and the bottom surface of the vortex-blocking disc. Specifically, the vortex-blocking disc can be flat or umbrella-shaped; in this embodiment, it is umbrella-shaped, and its outer diameter is larger than the inlet diameter of the drainage hopper. Its function is to isolate air when full-pipe flow is formed and to guide water flow evenly into the inlet along its bottom circumference. This prevents vortices from forming at the inlet of the rainwater hopper, avoids air being sucked into the drainage pipe, thereby maintaining the full-pipe, air-free state of the siphon system and ensuring siphon drainage efficiency. The cantilever rod is fixedly installed in the drainage hopper by a bracket to stably support the vortex-blocking disc; specifically, it is detachably installed on the drainage hopper by a grid plate.

[0022] Reference Figure 2 , Figure 3 and Figure 6 The reducing assembly includes an annular elastic reducing throat disposed on the inner wall of the upper end of the drain pipe. The elastic reducing throat has an annular cavity surrounding its circumference. The annular cavity is connected to the downstream negative pressure zone of the drain pipe through a pressure guiding pipe. Generally, this downstream negative pressure zone is located in the range of about 3m below the top of the drain pipe. Specifically, the outer wall of the elastic reducing throat is fixed to the inner wall of the drain pipe, and the inner wall can adaptively deform according to the change in the volume of the annular cavity.

[0023] Reference Figure 2 , Figure 3 and Figure 5 The jet-assisted obstacle removal assembly includes an air intake channel that runs longitudinally through the interior of the vortex baffle and the cantilever rod. The top of the air intake channel is connected to the atmosphere via an air inlet valve located on the top of the vortex baffle. The bottom of the air intake channel is connected to a Venturi nozzle located at the end of the cantilever rod. In particular, the jet orifice of the Venturi nozzle is located on its sidewall and is angled towards the annular water inlet gap to ensure that the jet can accurately target areas where blockages tend to accumulate.

[0024] Furthermore, under full-pipe drainage conditions, the normal siphon negative pressure generated in the downstream negative pressure zone of the drain pipe draws gas from the annular cavity through the pressure guide pipe, driving the elastic variable-diameter throat to contract towards the inner wall of the drain pipe to increase the drainage flow area; under extreme negative pressure conditions where the annular water inlet gap is blocked by flexible debris, the transient extreme negative pressure in the drain pipe overcomes the set resistance and draws open the air inlet valve, and the external air is accelerated at the Venturi nozzle through the air intake channel to form a high-speed jet that blows off the blockage at the annular water inlet gap.

[0025] Therefore, under normal rainfall or full-pipe drainage conditions, water flows into the drainage pipe through the annular inlet gap between the vortex baffle and the drainage hopper inlet. This reduces the probability of air entering the drainage pipe, allowing a stable siphon effect downstream of the pipe due to the height difference to quickly form a full-pipe siphon flow, improving drainage efficiency. At this time, the negative pressure downstream of the drainage pipe is transmitted through the pressure guide pipe to the annular cavity of the flexible reducing throat, slowly drawing gas from the annular cavity. This causes the flexible reducing throat to contract towards the inner wall of the drainage pipe under the pressure difference, thereby expanding the effective flow area of ​​the pipe, reducing drainage resistance, and further ensuring drainage efficiency.

[0026] When the annular inlet gap is largely blocked by flexible debris (such as plastic film), the water flow in the drain pipe is interrupted or significantly weakened. The remaining water column falls under gravity, creating a vacuum effect. This results in a transient extreme negative pressure in the upper section of the drain pipe that far exceeds normal values. This transient extreme negative pressure acts upwards on the bottom of the air inlet valve, overcoming its opening yield resistance threshold and drawing it open. External air rushes into the air intake channel, accelerates through the Venturi nozzle, and is then ejected obliquely from the side wall jet holes, forming a high-speed jet or air knife that directly impacts the debris blocking the annular inlet gap, blowing it off or tearing it away. At the same time, the air intake process itself releases the transient extreme negative pressure in the drain pipe, relieving the overload suction on the elastic variable diameter throat and preventing irreversible tensile damage. The entire process of identification, triggering, clearing, depressurization, and protection is completed entirely by the fluid energy within the system, without the need for any sensors or external energy sources.

[0027] Specifically, refer to Figure 2 , Figure 3 and Figure 4 The intake valve includes a valve body with its head end connected to the atmosphere and its tail end connected to the air intake channel, a normally closed valve core that slides and seals on the fluid passage inside the valve body, and a pre-tightening locking assembly located between the valve body and the normally closed valve core. The normally closed valve core blocks the fluid passage when closed and opens it when open. The pre-tightening locking assembly includes a return spring and a magnetic attraction mechanism. The return spring provides an upward closing force, and the magnetic attraction mechanism provides an upward static magnetic attraction force. The combined force of these two forces constitutes a defined, non-linear opening yield resistance threshold. The magnetic attraction mechanism includes a static magnetic component fixedly installed at the top of the valve body and a moving magnetic component fixed to the top of the normally closed valve core. The two components are magnetically attracted to each other. Both the moving and static magnetic components can be permanent magnets, or one can be a permanent magnet and the other can be made of a magnetically conductive material; the specific selection depends on the required attraction force.

[0028] For example, the inner wall of the air inlet at the valve body head end is provided with a tapered sealing surface, which gradually narrows from the inner wall of the valve body towards the head end, forming a conical annulus shape. The normally closed valve core near the valve body head end is provided with a sealing cone surface that is airtightly fitted to the tapered sealing surface in shape and size. This conical sealing structure, compared to a planar seal, has advantages such as self-centering, high contact stress, and high sealing reliability. The moving magnetic component is fixedly installed on the end face of the normally closed valve core with the sealing cone surface, while the stationary magnetic component is fixed to the inner wall of the tapered end of the valve body with the tapered sealing surface. Therefore, when the normally closed valve core is in the closed state, the moving magnetic component and the stationary magnetic component are at their minimum distance, the static magnetic attraction is maximized, and the locking effect on the normally closed valve core is strongest.

[0029] In addition, a support platform is provided at the tail end of the valve body. The support platform is in the shape of annular steps, and a central through hole connecting the fluid passage and the air intake passage is provided in the middle. In the initial state, the return spring is in a compressed state, with one end pressed against the tail end of the normally closed valve core and the other end pressed against the support platform, thereby applying a continuous elastic force to the normally closed valve core in the closing direction. When the normally closed valve core is pulled open and moves upward under the action of transient extreme negative pressure, the return spring is further compressed, providing a reset driving force for the normally closed valve core after the negative pressure is released.

[0030] Furthermore, to ensure that the normally closed valve core does not deviate or jam during operation, multiple positioning vanes are fixed to the inner wall of the valve body, spaced apart along its axial direction and circumferentially. The inner walls of these positioning vanes form a sliding space for the central part of the normally closed valve core to slide. The cross-sectional shape of the sliding space is adapted to the outer contour of the central part of the normally closed valve core. A fluid channel is formed between two adjacent positioning vanes for fluid to pass through. When the normally closed valve core is in the open state, the air inlet at the end of the valve body that connects to the atmosphere is connected to the air intake channel through the fluid channel between multiple sets of adjacent positioning vanes and the central through hole.

[0031] Therefore, under full-pipe drainage conditions, the drain pipe experiences normal siphon negative pressure. At this time, the central through-hole at the bottom of the normally closed valve core experiences a downward suction force. However, the absolute value of this suction force is less than the absolute value of the opening yield resistance threshold, which is formed by the closing force of the return spring and the static magnetic attraction force of the magnetic attraction mechanism. Therefore, the normally closed valve core remains closed, and the sealing cone surface and the closing cone surface seal tightly. It is important to emphasize here that because the moving and static magnetic components attract each other and have the smallest distance in this state, the static magnetic attraction force is at its maximum value. This effectively resists the slight tumbling or minor vibration that may be caused by normal siphon negative pressure, fundamentally eliminating the possibility of slow leakage near the critical point of conventional spring valves, ensuring that the air intake channel is tightly closed and normal siphon drainage is not disturbed in any way.

[0032] When the annular inlet gap is blocked by flexible debris, the negative pressure in the drain pipe surges rapidly to a transient extreme negative pressure. This negative pressure acts on the tail end of the normally closed valve core through the air intake channel and the central through hole, forming a downward fluid pressure differential suction force. Once this suction force exceeds the opening yield resistance threshold, the normally closed valve core begins to move downward, and the sealing cone surface separates from the constriction cone sealing surface. At the same time, the moving magnetic component separates from the stationary magnetic component, and the distance between them increases from zero or a minimum value. It is worth noting that the magnetic attraction force decreases sharply with the increase of the separation distance of the magnetic components in an inverse square relationship. Therefore, at the moment the moving magnetic component separates from the stationary magnetic component, the upward static magnetic attraction force acting on the normally closed valve core drops sharply, causing the upward combined resistance on the normally closed valve core to decrease significantly in a very short time. The normally closed valve core can instantly overcome the remaining resistance and jump to the maximum opening before the return spring is further compressed significantly, making the air inlet of the valve body fully open. The entire activation process is characterized by a non-linear, step-like "jump" action, which instantly transforms the vacuum potential energy accumulated in the system into an explosive burst of induced draft energy.

[0033] After the valve body inlet is fully opened, external air rushes into the air intake channel at high speed and large flow rate. After being accelerated by the Venturi nozzle, it forms a high-speed jet that blows away the blockage at the annular water inlet gap. At the same time, the introduction of a large amount of external air also quickly releases the transient extreme negative pressure in the drain pipe. As the negative pressure is released, the suction force acting on the tail end of the normally closed valve core rapidly decreases to below the elastic force of the return spring. The normally closed valve core then returns to its original position under the drive of the return spring, the sealing cone surface re-fits the sealing surface of the concave cone surface, the moving magnetic component and the stationary magnetic component re-attract, and the air intake valve returns to its normally closed state. The entire jet clearing and pressure relief protection process is completed in one complete cycle of "sudden opening - air intake - pressure relief - reset".

[0034] It should be noted that the absolute value of the opening yield resistance threshold of the air intake valve must be greater than the absolute value of the normal siphon negative pressure of the drain pipe under full-pipe drainage conditions to ensure that accidental opening never occurs under normal siphon conditions. Simultaneously, this absolute value must be less than the absolute value of the ultimate tensile pressure required for irreversible tensile failure of the flexible reducing throat, ensuring that the air intake valve has already opened and released pressure before the negative pressure reaches the level that would damage the throat. The specific value of this opening yield resistance threshold can be calculated based on the actual siphon head height of the building and the mechanical parameters of the selected flexible reducing throat, and can be physically calibrated by adjusting the preload of the return spring or by using magnetic components of different magnetic strength levels.

[0035] Specifically, under extreme negative pressure, the area above the drainage hopper is submerged in water, meaning the air inlet of the air intake valve at the top of the baffle plate is likely also below the water surface. At this time, the air intake valve opens, drawing in water, a water-air mixture, or pure air, but none of these will significantly affect the clearing effect of the Venturi nozzle jet.

[0036] In some embodiments, refer to Figure 2 A grazing angle is formed between the axis of the jet orifice on the Venturi nozzle and the virtual plane where the annular water inlet gap is located; for example, the grazing angle can be selected in the range of 5°-15°, which allows the jet to act on the thin film-like debris with a shallow angle of entry, which is beneficial to lift the film off the adsorption surface.

[0037] In other embodiments, reference is made to Figure 3 and Figure 5 The Venturi nozzle has a flexible duckbill valve surrounding its jet orifice on its sidewall. The flexible duckbill valve can be made of materials with good weather resistance and elasticity, such as silicone rubber or fluororubber, and its end has a flat lip slit. In this way, under full-pipe drainage, the water pressure in the drainage hopper makes the slit of the flexible duckbill valve lip tightly closed, preventing external mud or debris from flowing back into the air intake channel; under extreme negative pressure, the high-speed airflow in the air intake channel forces open the flexible duckbill valve from the inside, and is shaped into a jet air knife with a flat cross-section by the squeezing and guiding action of its lip.

[0038] In some embodiments, to overcome the problem of water flow pulsation during full-pipe drainage being transmitted to the annular cavity of the elastic variable-diameter throat through the pressure-conducting pipe, causing frequent micro-movements and accelerated fatigue of the elastic variable-diameter throat, the pressure-conducting pipe is preferably a capillary tube with an inner diameter of less than 2 mm. Furthermore, the inner diameter flow resistance parameter of the pressure-conducting pipe is designed to match the volume of the annular cavity of the elastic variable-diameter throat. The goal of this matching is to ensure that the gas filling and releasing rate within the annular cavity is less than the short-term negative pressure change rate caused by water flow pulsation in the drain pipe. Exemplarily, the pressure-conducting pipe can be a polytetrafluoroethylene capillary tube, a polyurethane capillary tube, or a 304 / 316L stainless steel capillary tube.

[0039] Therefore, high-frequency, short-duration hydraulic pressure pulsations are effectively attenuated when passing through the high-resistance capillary pressure-conducting tube. Their energy is insufficient to drive significant inflation and deflation of the gas within the annular cavity within a single pulsation cycle, thus the elastic variable-diameter throat does not respond to these pulsations. However, continuous, low-frequency normal siphon negative pressure changes can be effectively transmitted, driving the elastic variable-diameter throat to smoothly contract or return to its original position. In this way, the elastic variable-diameter throat's movement possesses damping delay characteristics, is unaffected by short-duration hydraulic fluctuations, and improves the system's operational stability and component lifespan.

[0040] In other embodiments, to further address the problem of unstable pressure tapping and easy clogging at the end of the pressure-conducting pipe in high-speed water flow containing impurities, refer to Figure 2 , Figure 3 and Figure 6A pressure tap is installed at the end of the pressure-conducting pipe connected to the negative pressure zone downstream of the drain pipe. The pressure tapping hole of the pressure tap is opened on the back flow surface of the water flow, making it difficult for solid particles carried in the water flow to turn back and enter under the action of inertia, thus reducing the probability of blockage geometrically. In addition, the pressure tap is also covered by a static pressure shield with one end open downwards. When the high-speed full-pipe water flow passes through the outer surface of the static pressure shield, an entrainment effect is generated in the lower opening area, entraining and carrying away the fluid and debris in this area, so that a relatively static pressure cavity is formed inside the shield. The pressure in this static pressure cavity is the stable static pressure of the flow field node, which is transmitted to the elastic variable diameter throat through the pressure tap and pressure-conducting pipe, while the debris in the water flow moves downstream with the main flow and is difficult to enter the interior of the shield.

[0041] Furthermore, the pressure tapping head is further secured with multiple circumferentially distributed, radially extending, arc-shaped springs. These springs can be made of materials with good elasticity and fatigue resistance, such as spring steel or beryllium copper alloy. During installation, the pressure tapping head assembly is inserted into the drain pipe. The arc-shaped springs deform under pressure and, through their elastic restoring force, press against the inner wall of the drain pipe, thereby coaxially suspending and anchoring the pressure tapping head and static pressure shield in the center region of the flow field within the drain pipe. This flexible anchoring method eliminates the need for drilling holes in the drain pipe wall for fixation. It effectively absorbs the energy of water flow pulsations, prevents vibration fatigue fracture of the pressure guide pipe, and ensures that the pressure tapping point remains at the most stable position in the center of the flow field, guaranteeing the consistency and long-term reliability of pressure signal acquisition.

[0042] In some embodiments, refer to Figure 2 and Figure 3 In the initial state before being subjected to negative pressure suction, the flexible variable diameter throat is preferably funnel-shaped with a larger top and smaller bottom and a gradually narrowing cross section, which is conducive to guiding the water flow smoothly and reducing local resistance loss. Moreover, the thickness of its pipe wall gradually decreases from top to bottom, making the lower end of the throat more sensitive to changes in negative pressure. It can preferentially undergo radial contraction under normal siphon negative pressure conditions, making the response more sensitive and the process of adjusting the flow area smoother.

[0043] This application discloses a construction method for building roof drainage, based on the above-described building roof drainage structure, with reference to... Figure 1 , Figure 2 and Figure 4 It includes the following steps: S1. Structural Positioning and Layout: Fix the drainage hopper to the roof gutter or low-lying area of ​​the catchment area, ensuring that the installation base is flat and reliably sealed. Connect the drainage pipe vertically downwards and connect and check for leaks according to the siphon sealing requirements. Insert the pressure guide pipe into the drainage pipe from the inside of the drainage hopper, and extend the pressure tap at its end to the point of maximum negative pressure of the fluid at a vertical distance of more than 3 meters from the drainage hopper.

[0044] S2. Jet orientation configuration: When assembling the flow guide assembly, adjust the circumferential installation angle of the cantilever rod according to the gutter direction and the local prevailing wind direction, so that the center of the jet hole of the Venturi nozzle at the end of the cantilever rod is aligned with the area in the annular water inlet gap that is most susceptible to wind-driven film or fluff accumulation. Then lock the relative position between the cantilever rod and the flow deflector.

[0045] S3. Physical calibration of anti-interference threshold: Obtain the design full-pipe siphon head height difference from the building roof to the ground, and calculate the peak value of normal siphon negative pressure in the drainage pipe accordingly; at the same time, obtain the absolute value of the tensile failure limit negative pressure of the installed flexible reducer; by adjusting the initial force parameters of the pre-tightening locking component in the air inlet valve, such as adjusting the pre-tightening force of the return spring or selecting moving / stationary magnetic components of different magnetic force levels, ensure that the absolute value of the opening yield resistance threshold of the air inlet valve is strictly between the absolute value of the peak value of normal siphon negative pressure and the absolute value of the tensile failure of the flexible reducer.

[0046] S4. Extreme Working Condition Simulation and Linkage Testing: Water is injected into the roof catchment area to submerge the drainage hopper. A flexible membrane is used to completely seal the annular water inlet gap of the drainage hopper, causing the residual water in the drainage pipe to fall and generate a transient extreme negative pressure. Then, it is tested whether the air inlet valve is sucked open within a specified time and produces a identifiable sudden jump, whether the Venturi nozzle ejects a high-speed airflow to push the flexible membrane open and fall off, and whether the elastic variable diameter throat returns to its original state after depressurization. When all three indicators are met, the jet clearing and anti-diaphragm tear linkage configuration is deemed qualified, and the system can be put into normal use.

[0047] The implementation principle of a roof drainage structure for a building according to an embodiment of this application is as follows: During normal rainfall, roof water flows through the drain hopper into the annular inlet gap, then into the drain pipe, forming a full-pipe siphon flow. Downstream of the drain pipe, negative pressure enters the annular cavity of the flexible reducing throat through the pressure guide pipe. After the air in the cavity is extracted, the inner wall of the flexible reducing throat retracts inward, reducing its occupation of the main flow and maintaining a large effective flow area at the upper end of the drain pipe. Simultaneously, the air inlet valve remains normally closed under the combined action of the return spring and the magnetic attraction mechanism, preventing air from entering the pipe under normal negative pressure and disrupting the siphon continuity. It is important to emphasize that the negative pressure in this stage serves both as the drainage drive and the diameter adjustment function, with both working synergistically through the same fluid state.

[0048] When flexible films, lint, and other debris cover the annular inlet gap and gradually form a blockage, the obstructed water inflow further deepens the negative pressure inside the drain pipe. At this point, the transient negative pressure, reaching a preset limit, overcomes the opening threshold of the air inlet valve, causing the normally closed valve core to open. The moving and stationary magnetic components quickly separate, the magnetic attraction force rapidly weakens, and the air intake channel is instantly connected to the atmosphere. Outside air or a mixture of air and water enters the Venturi nozzle through the air intake channel, is accelerated, and is then sprayed through the sidewall jet holes towards the annular inlet gap, forming a directional fluid jet that blows off or peels away the blockage. As the air is released, the negative pressure drops, and the normally closed valve core recloses under the action of the return spring and magnetic attraction mechanism, returning the system to a stable drainage state.

[0049] If combined with capillary pressure guide tubes, static pressure shields, and bow-shaped springs, the stability of the pressure tapping point of the pressure guide tube will be further improved, and the contraction and reset of the elastic variable diameter throat will be more likely to keep in line with the actual negative pressure changes, thereby reducing vibration and malfunctions.

[0050] Unless otherwise defined, the technical or scientific terms used in this application shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," "third," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "comprising" or "including" and similar terms mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including" and their equivalents, and do not exclude other elements or objects. "Above," "below," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0051] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A roof drainage structure for a building, comprising a drainage hopper and a drainage pipe disposed below the drainage hopper, characterized in that, Also includes: The flow guiding component includes a vortex-blocking plate disposed above the inlet of the drainage bucket and a cantilever rod extending downward from the center of the vortex-blocking plate, with an annular inlet gap formed between the outer edge of the inlet of the drainage bucket and the bottom surface of the vortex-blocking plate. The variable diameter assembly includes an annular elastic variable diameter throat disposed on the inner wall of the upper end of the drain pipe, the elastic variable diameter throat having an annular cavity and the annular cavity being connected to the downstream negative pressure zone of the drain pipe through a pressure guiding pipe. as well as The jet clearing assembly includes an air intake channel that runs longitudinally through the vortex baffle and the cantilever rod. The top of the air intake channel is connected to the atmosphere and an air inlet valve is provided on the top of the vortex baffle. The bottom of the air intake channel is connected to a Venturi nozzle located at the end of the cantilever rod. The jet orifice of the Venturi nozzle is located on its side wall and is obliquely directed toward the annular water inlet gap. In the case of full-pipe drainage, the normal siphon negative pressure generated in the negative pressure zone downstream of the drainage pipe draws gas from the annular cavity through the pressure guide pipe, causing the elastic variable-diameter throat to contract towards the inner wall of the drainage pipe to increase the drainage flow area; in the case of extreme negative pressure where the annular water inlet gap is blocked by flexible debris, the transient extreme negative pressure in the drainage pipe overcomes the set resistance and draws open the air inlet valve, and the external air is accelerated at the Venturi nozzle through the air duct to form a high-speed jet that blows off the blockage at the annular water inlet gap.

2. The roof drainage structure for a building according to claim 1, characterized in that, The intake valve includes a valve housing with one end open to the atmosphere, a normally closed valve core that is slidably sealed in the fluid passage inside the valve housing, and a pre-tightening locking assembly disposed between the valve housing and the normally closed valve core. The pre-tightening locking assembly includes a return spring that presses against the valve body and the normally closed valve core, and a magnetic attraction mechanism. The sum of the closing force of the return spring and the static magnetic attraction force of the magnetic attraction mechanism constitutes an opening yield resistance threshold. The absolute value of the opening yield resistance threshold is greater than the absolute value of the normal siphon negative pressure of the drainage pipe under full pipe drainage conditions, and less than the absolute value of the ultimate tensile pressure of the elastic variable diameter throat when it undergoes irreversible tensile failure.

3. The roof drainage structure for a building according to claim 2, characterized in that, The magnetic attraction mechanism includes a static magnetic component fixedly installed inside the top of the valve housing and a moving magnetic component fixedly installed on the top of the normally closed valve core, and the two are magnetically attracted to each other. When the annular inlet gap does not reach the limit negative pressure state, the moving magnetic component and the stationary magnetic component attract each other to limit the micro-leaking of the normally closed valve core under normal siphon negative pressure; When the negative pressure in the drain pipe reaches the transient extreme negative pressure, the normally closed valve core is subjected to downward fluid pressure difference suction force to overcome the opening yield resistance threshold. The moving magnetic component instantly detaches from the stationary magnetic component. The static magnetic attraction force decreases sharply as the separation distance of the magnetic components increases, so that the normally closed valve core instantly overcomes the elastic force of the return spring to reach the maximum opening degree, causing the air passage to be fully opened to form an explosive high-speed jet.

4. A roof drainage structure for residential buildings according to claim 2, characterized in that, While the air intake channel is opened and airflow is introduced at high speed, the introduced external air releases the transient extreme negative pressure in the drain pipe, drives the normally closed valve core to reset and close under the action of the pre-tightening locking assembly, and releases the transient overload suction on the elastic variable diameter throat. The jet orifice axis of the Venturi nozzle forms a grazing angle of 5°-15° with the virtual plane containing the annular water inlet gap.

5. A roof drainage structure for residential buildings according to claim 1, characterized in that, The sidewall of the Venturi nozzle is covered with an elastic duckbill valve around its jet orifice. When the pipe is fully drained, the water pressure in the drain hopper causes the slit of the elastic duckbill valve lip to close, preventing external mud and sand from flowing back into the air intake channel. Under extreme negative pressure, the high-speed airflow in the air intake duct forces open the elastic duckbill valve and is squeezed by the lip of the elastic duckbill valve to form a flat jet air knife.

6. A roof drainage structure for residential buildings according to claim 1, characterized in that, In the initial state without negative pressure suction, the elastic variable diameter throat has a funnel shape with a gradually narrowing cross section from top to bottom, and the wall thickness of the elastic variable diameter throat gradually decreases from top to bottom.

7. A roof drainage structure for residential buildings according to claim 1, characterized in that, The pressure guiding tube is a capillary tube with an inner diameter of less than 2 mm. The inner diameter flow resistance parameter of the pressure guiding tube is matched with the volume of the annular cavity of the elastic variable diameter throat, so that the gas filling and releasing rate in the annular cavity is less than the short-term negative pressure change rate caused by the water flow pulsation in the drain pipe. This makes the contraction and reset action of the elastic variable diameter throat unaffected by short-term hydraulic fluctuations and has damping delay characteristics.

8. A roof drainage structure for residential buildings according to claim 1, characterized in that, The pressure guide pipe is connected to the end of the negative pressure zone downstream of the drain pipe and is equipped with a pressure tapping head. The pressure tapping hole of the pressure tapping head is opened on the back flow surface of the water flow, and the pressure tapping head is covered with a static pressure shield with one end open downward, so as to use the ejection effect generated by the water flow through the static pressure shield to extract impurities and extract stable static pressure.

9. A roof drainage structure for a building according to claim 8, characterized in that, The pressure tapping head is fixed with multiple bow-shaped spring pieces that are evenly distributed around the circumference and extend radially outward. The bow-shaped spring pieces are deformed under pressure and abut against the inner wall of the drain pipe, so as to suspend and anchor the pressure tapping head and the static pressure shield in the center region of the flow field of the drain pipe, thereby avoiding the pressure guide pipe from being subjected to vibration fatigue and pressure tapping point displacement under the scouring of the high-speed siphon full pipe water flow.

10. A construction method for a building roof drainage structure, based on a building roof drainage structure as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Structural positioning and arrangement: Fix the drainage hopper to the roof gutter or the low-lying area of ​​the catchment area, and connect it vertically downward to the drainage pipe; insert the pressure guide pipe into the drainage pipe through the drainage hopper, and extend the pressure tap at the end of the pressure guide pipe downward to the point of maximum negative pressure of the fluid at a vertical distance of more than 3 meters from the drainage hopper. S2. Jet orientation configuration: When assembling the flow guide assembly, adjust the circumferential installation angle of the cantilever rod according to the direction of the gutter, so that the center of the jet hole of the Venturi nozzle at the end of the cantilever rod is aligned with the area of ​​the annular water inlet gap that is most susceptible to wind-driven film or fluff accumulation. S3. Physical calibration of anti-interference threshold: Obtain the design full-pipe siphon head height difference from the building roof to the ground, and calculate the peak value of normal siphon negative pressure in the drainage pipe accordingly; by adjusting the initial force parameters of the pre-tightening locking component in the air inlet valve, ensure that the absolute value of the opening yield resistance threshold of the air inlet valve is strictly between the absolute value of the peak value of normal siphon negative pressure and the absolute value of the tensile failure of the elastic variable diameter throat.

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