A foam shield system with a mechanically self-regulating flow device

Abstract

This utility model discloses a foam shield system with a mechanically self-regulating flow device, belonging to the field of foam shields. It includes a base, a foam storage tank, an inlet valve, a switching valve, a chemical mixing tank, a peristaltic pump, a foam generator, and a flow regulating device integrated on the base. The flow regulating device includes a valve body with water inlets at both ends. A frustum-shaped valve core, which can slide axially, is disposed within the valve body cavity. The larger diameter end of the frustum-shaped valve core faces the water inlet direction of the valve body, and the smaller diameter end faces the water outlet direction of the valve body. An annular flow channel is formed between the frustum-shaped valve core and the valve body cavity. In this foam shield system with a mechanically self-regulating flow device, when the water pressure increases from 0.1 MPa to 0.8 MPa, the thrust of the water pressure on the larger diameter end of the valve core increases, pushing the valve core to compress the spring axially. At this time, the cross-sectional area of ​​the annular flow channel decreases linearly with the slope of the cone surface, and the narrowing of the flow channel offsets the effect of the increased water pressure. Conversely, when the water pressure decreases, the spring force pushes the valve core back to its original position, increasing the cross-sectional area of ​​the flow channel and compensating for water loss.

Description

Technical Field

[0001] This utility model relates to the field of foam shield technology, specifically to a foam shield system with a mechanically self-regulating flow device. Background Technology

[0002] The foam shield system with a mechanical self-regulating flow device is a core functional module of smart toilets. It achieves splash prevention, odor isolation, and antibacterial effects by forming a uniform foam layer on the toilet bowl surface. The stability of foam quality directly depends on the mixing ratio of water and foam solution in the mixing tank. Currently, foam shield systems with mechanical self-regulating flow devices on the market generally face the technical challenge of unstable flow due to water pressure fluctuations. Household tap water pressure often fluctuates dynamically between 0.1MPa and 0.8MPa. When the water pressure suddenly increases, the amount of water entering the mixing tank surges, diluting the foam solution concentration and resulting in thin foam with insufficient coverage. Conversely, when the water pressure suddenly drops, the water volume decreases sharply, leading to excessively high foam solution concentration, easy foam breakage, and increased costs.

[0003] To address this issue, existing technologies primarily employ two types of adjustment schemes, both of which have significant drawbacks: one is the electronically controlled flow regulation scheme, which detects water pressure through a pressure sensor and then adjusts the valve opening using a solenoid valve or servo motor. While this achieves precise control, it requires additional electronic components such as controllers and wiring harnesses, increasing system costs by more than 30%. Furthermore, the humid environment of bathrooms can easily lead to short circuits, sensor malfunctions, and other failures, resulting in insufficient reliability. The other is the mechanical adjustment scheme, such as a structure using a single spring and a flat valve core. However, its adjustment accuracy is poor—the cross-sectional area of ​​the flow channel between the flat valve core and the valve body changes in a stepped manner with displacement, making it impossible to linearly match water pressure fluctuations. Moreover, the single spring can easily cause uneven force on the valve core, and long-term use can lead to jamming due to tilting, further exacerbating flow fluctuations.

[0004] Therefore, the market urgently needs a foam shield system with a mechanically self-regulating flow device that requires no electronic control components, has a simple and reliable structure, and can achieve stable flow through purely mechanical self-regulation. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a foam shield system with a mechanically self-regulating flow device.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is: a foam shield system with a mechanical self-regulating flow device, including a base, a foam storage tank, an inlet valve, a switching valve, a liquid mixing tank, a peristaltic pump, a foamer, and a flow regulating device integrated on the base;

[0007] The flow regulating device includes a valve body with water inlets at both ends. A frustum-shaped valve core that can slide axially is provided in the inner cavity of the valve body. The large-diameter end of the frustum-shaped valve core faces the water inlet direction of the valve body, and the small-diameter end faces the water outlet direction of the valve body. An annular flow channel is formed between the frustum-shaped valve core and the inner cavity of the valve body.

[0008] The valve body is provided with a limiting seat at the outlet end. A plurality of compression springs are provided at the end of the limiting seat facing the frustum-shaped valve core. The end of the compression springs away from the limiting seat is connected to the frustum-shaped valve core through a connecting plate.

[0009] The limiting seat has a through hole for water to flow through.

[0010] In the above technical solution, the large-diameter end of the frustum-shaped valve core faces the water inlet direction, and its conical surface forms an annular flow channel with the inner wall of the valve body. When the water pressure increases from 0.1MPa to 0.8MPa, the thrust of the water pressure on the large-diameter end of the valve core increases, pushing the valve core to compress the spring axially. At this time, the cross-sectional area of ​​the annular flow channel decreases linearly with the slope of the conical surface, and the narrowing of the flow channel offsets the effect of the increased water pressure. Conversely, when the water pressure decreases, the spring force pushes the valve core to reset, and the cross-sectional area of ​​the flow channel increases, compensating for water loss. This linear relationship between "water pressure-displacement-flow channel area" can reduce the impact of water pressure on water volume and ensure a stable flow of water entering the chemical mixing tank.

[0011] Preferably, the cone angle of the frustum-shaped valve core is 25°-45°, and the diameter of the larger diameter end of the frustum-shaped valve core is 0.5-2mm smaller than the inner diameter of the valve body.

[0012] Preferably, the spring constant is 1-5 N / mm, and the initial pre-compression is 3-8 mm.

[0013] Preferably, the number of compression springs is four, and the compression springs are arranged in a circular array around the central axis of the limiting seat.

[0014] Preferably, a guide rod is inserted through the central hole of the compression spring, and a guide hole is provided in the limiting seat for the guide rod to slide. One end of the guide rod is fixedly connected to the connecting plate, and the other end of the guide rod is slidably connected to the guide hole.

[0015] Preferably, one end of the inlet valve is connected to a water source pipeline, and the other end is connected to a flow regulating device. The outlet of the flow regulating device is connected to the inlet of the switching valve, the outlet of the switching valve is connected to the inlet of the medicine mixing tank, the outlet of the foam storage tank is connected to the air inlet of the peristaltic pump, and the air outlet of the peristaltic pump is connected to the medicine inlet of the medicine mixing tank.

[0016] Preferably, the total flow area of ​​the through hole is 48% to 60% of the cross-sectional area corresponding to the nominal diameter of the valve body, and the total flow area of ​​the through hole is not less than 1.2 times the maximum cross-sectional area of ​​the annular flow channel.

[0017] Compared with the prior art, the beneficial effects of this utility model are:

[0018] 1. This foam shield system with a mechanically self-regulating flow device features a frustum-shaped valve core with its large-diameter end facing the water inlet. Its conical surface and the inner wall of the valve body form an annular flow channel. When the water pressure increases from 0.1 MPa to 0.8 MPa, the thrust of the water pressure on the large-diameter end of the valve core increases, pushing the valve core to compress the spring axially. At this time, the cross-sectional area of ​​the annular flow channel decreases linearly with the slope of the conical surface, narrowing the flow channel to offset the effect of the increased water pressure. Conversely, when the water pressure decreases, the spring force pushes the valve core back to its original position, increasing the cross-sectional area of ​​the flow channel to compensate for water loss. This linear relationship between water pressure, displacement, and flow channel area reduces the impact of water pressure on water volume, ensuring a stable flow of water entering the chemical mixing tank.

[0019] 2. This foam shield system with a mechanically self-regulating flow device eliminates the need for sensors, solenoid valves, or other electronic components during the entire adjustment process. It achieves self-regulation solely through mechanical force balance, completely resolving the short-circuit and corrosion failure issues common in humid bathroom environments with electronic control solutions. Furthermore, the frustum-shaped valve core, compression spring, and valve body can all be mass-produced using injection molding or metal stamping processes. Compared to electronic control solutions, the material cost per flow regulating device is lower, and the elimination of circuit debugging steps improves assembly efficiency.

[0020] 3. This foam shield system with a mechanically self-regulating flow device limits the cone angle of the frustum-shaped valve core to 25°-45°, and the diameter of the large-diameter end is 0.5-2mm smaller than the inner diameter of the valve body. This ensures that the initial clearance of the annular flow channel is adapted to the flow requirements of the foam shield system with the mechanically self-regulating flow device. A cone angle that is too small will cause the flow channel cross-sectional area to change too slowly with displacement, resulting in insufficient adjustment sensitivity; a cone angle that is too large will cause the flow channel to change too quickly, easily leading to sudden changes in flow rate. The initial clearance formed by the 0.5-2mm diameter difference ensures the basic flow rate at low pressure and provides sufficient compression space for adjustment at high pressure, keeping the flow fluctuation within a certain range and further improving the stability of the mixing ratio. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0022] Figure 2 This is a three-dimensional structural schematic diagram of the present invention from another perspective.

[0023] Figure 3 This utility model Figure 1 A magnified structural diagram of point A in the middle.

[0024] Figure 4 This is a cross-sectional view of the flow regulating device of this utility model.

[0025] In the diagram: 1. Base; 2. Foam storage tank; 21. Liquid inlet; 3. Water inlet valve; 4. Switching valve; 5. Medicine mixing tank; 6. Peristaltic pump; 7. Foamer; 8. Flow regulating device; 81. Valve body; 82. Frustum-shaped valve core; 83. Limit seat; 831. Through hole; 84. Compression spring; 85. Connecting plate; 86. Guide rod; 9. Water source pipeline; 10. Pipeline. Detailed Implementation

[0026] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0027] Please refer to Figures 1 to 4 A foam shield system with a mechanical self-regulating flow device in this embodiment includes a base 1, a foam storage tank 2, a water inlet valve 3, a switching valve 4, a liquid mixing tank 5, a peristaltic pump 6, a foam generator 7, and a flow regulating device 8 integrated on the base 1.

[0028] The flow regulating device 8 includes a valve body 81 with water inlets at both ends. The valve body 81 is tubular, and its two ends are connected to the inlet valve 3 and the pipeline 10 respectively through flanges. A frustum-shaped valve core 82 that can slide axially is provided in the inner cavity of the valve body 81. The large-diameter end of the frustum-shaped valve core 82 faces the water inlet direction of the valve body 81, and the small-diameter end faces the water outlet direction of the valve body 81. An annular flow channel is formed between the frustum-shaped valve core 82 and the inner cavity of the valve body 81.

[0029] The outlet end of the valve body 81 is provided with a limiting seat 83. A number of compression springs 84 are provided at one end of the limiting seat 83 facing the frustum-shaped valve core 82. The end of the compression springs 84 away from the limiting seat 83 is connected to the frustum-shaped valve core 82 through a connecting plate 85.

[0030] The limiting seat 83 has a through hole 831 for water to flow through.

[0031] In the above scheme, the large-diameter end of the frustum-shaped valve core 82 faces the water inlet direction, and its conical surface forms an annular flow channel with the inner wall of the valve body 81. When the water pressure rises from 0.1MPa to 0.8MPa, the thrust of the water pressure on the large-diameter end of the valve core increases, pushing the valve core to compress the spring 84 axially. At this time, the cross-sectional area of ​​the annular flow channel decreases linearly with the slope of the conical surface, and the narrowing of the flow channel offsets the effect of the increased water pressure. Conversely, when the water pressure decreases, the spring force pushes the valve core to reset, and the cross-sectional area of ​​the flow channel increases, compensating for water loss. This linear relationship between water pressure, displacement, and flow channel area can reduce the influence of water pressure on water volume and ensure a stable water volume entering the chemical mixing tank 5.

[0032] The entire adjustment process requires no electronic components such as sensors or solenoid valves, achieving self-adjustment solely through mechanical force balance. This completely solves the problems of short circuits and corrosion that occur with electronic control solutions in the humid environment of bathrooms. Furthermore, the frustum-shaped valve core 82, compression spring 84, and valve body 81 can all be mass-produced using injection molding or metal stamping processes. Compared to electronic control solutions, the material cost of a single flow regulation device 8 is lower, and the elimination of circuit debugging steps improves assembly efficiency.

[0033] The through hole 831 on the limit seat 83 is designed to ensure that the water flow passes through the regulating device without obstruction. Its total flow area is not less than 1.2 times the maximum cross-sectional area of ​​the annular flow channel. For example, if the maximum area of ​​the annular flow channel is 10 mm², the total area of ​​the through hole 831 is ≥12 mm². Combined with the streamlined design of the frustum-shaped valve core 82, the head loss of the entire flow regulating device 8 is controlled within 0.05 MPa, which is much lower than the 0.15 MPa of the existing mechanical solution. This ensures that there is still enough water to enter the chemical mixing tank 5 under low pressure, and avoids interruption of foam generation.

[0034] Preferably, the cone angle of the frustum-shaped valve core 82 is 25°-45°, and the large diameter end diameter of the frustum-shaped valve core 82 is 0.5-2mm smaller than the inner diameter of the valve body 81.

[0035] In the above scheme, the cone angle of the frustum-shaped valve core 82 is limited to 25°-45°, and the diameter of the large-diameter end is 0.5-2mm smaller than the inner diameter of the valve body 81. This ensures that the initial clearance of the annular flow channel is adapted to the flow requirements of the foam shield system with a mechanically self-regulating flow device. A cone angle that is too small will cause the flow channel cross-sectional area to change too slowly with displacement, resulting in insufficient adjustment sensitivity; a cone angle that is too large will cause the flow channel to change too quickly, easily leading to sudden changes in flow rate. The initial clearance formed by the 0.5-2mm diameter difference ensures the basic flow rate at low pressure and provides sufficient compression space for adjustment at high pressure, keeping the flow fluctuation within a certain range and further improving the stability of the mixing ratio.

[0036] Preferably, the spring constant of the compression spring 84 is 1-5 N / mm, and the initial pre-compression is 3-8 mm.

[0037] In the above scheme, an excessively small stiffness coefficient will cause the valve core to displace excessively at low pressure, resulting in insufficient flow due to an overly narrow flow channel; conversely, an excessively large stiffness coefficient will make it difficult for the valve core to move at high pressure, leading to insufficient flow channel adjustment and excessive flow. An initial pre-compression of 3-8mm ensures that the spring generates effective thrust at a water pressure of 0.1MPa, preventing the valve core from malfunctioning due to its own weight or minor water pressure fluctuations. This ensures that the valve core displacement has a strictly linear relationship with water pressure changes, and also results in a faster adjustment response.

[0038] Preferably, there are four compression springs 84, which are arranged in a ring array around the central axis of the limiting seat 83.

[0039] In the above scheme, the four springs can form a symmetrical force structure, controlling the radial offset of the valve core within 0.05mm, thus avoiding frictional wear between the valve core and the inner wall of the valve body 81 due to excessive local force. The annular array layout can also disperse the lateral force of water flow impact on the valve core, reducing the sliding resistance of the valve core by 20%, further reducing the risk of jamming, and ensuring that the adjustment accuracy is maintained even after long-term use.

[0040] Preferably, a guide rod 86 is inserted through the central hole of the compression spring 84, and a guide hole for sliding of the guide rod 86 is opened in the limiting seat 83. One end of the guide rod 86 is fixedly connected to the connecting plate 85, and the other end of the guide rod 86 is slidably connected to the guide hole.

[0041] In the above scheme, the fit between the guide rod 86 and the guide hole restricts the radial degree of freedom of the valve core, allowing it to slide only axially. The supporting effect of the guide rod 86 can counteract the lateral torque generated by the water flow impact, controlling the valve core tilt angle within 0.5° and avoiding uneven gaps in the annular flow channel caused by tilting. At the same time, the guide structure reduces the direct friction between the spring and the valve body 81, extending the spring's service life and ensuring the long-term stability of the regulating device.

[0042] One end of the inlet valve 3 is connected to the water source pipe 9, and the other end is connected to the flow regulating device 8. The outlet of the flow regulating device 8 is connected to the inlet of the switching valve 4. The outlet of the switching valve 4 is connected to the inlet of the medicine mixing tank 5. The outlet of the medicine mixing tank 5 is connected to the foamer 7. The outlet of the foam storage tank 2 is connected to the air inlet of the peristaltic pump 6. The air outlet of the peristaltic pump 6 is connected to the medicine inlet of the medicine mixing tank 5.

[0043] In the above scheme, the top of the foam storage tank 2 is provided with a liquid inlet 21, which is used to conveniently add foam. The foam storage tank 2 is fixedly installed on the base 1, realizing the integration of the foam generator 7 and the base 1. There is no need to place the foam storage tank 2 outside the toilet, which makes better use of space. The switching valve 4 is used to control the water flow, or to switch between foam generation and water flushing modes. When not in operation, the water flow is cut off to save water resources. The foam generator 7 has an 80-mesh stainless steel foaming net inside and a 2mm diameter air inlet hole on the side wall. When the mixed liquid passes through the foaming net at high speed, it carries air and forms fine foam with an average diameter of 0.5-2mm. The peristaltic pump 6 delivers part of the mixed liquid from the medicine mixing tank 5 and the foam liquid output from the foam storage tank 2 to the medicine mixing tank 5 again in proportion to realize secondary concentration adjustment.

[0044] It should be noted that the foam storage tank 2, water inlet valve 3, switching valve 4, chemical mixing tank 5, peristaltic pump 6, foamer 7 and flow regulating device 8 are all connected by pipes 10. The arrangement of pipes 10 is common knowledge in the prior art, so this application will not describe the arrangement of pipes 10 in detail. At the same time, this application does not make any improvements to the foam storage tank 2, water inlet valve 3, switching valve 4, chemical mixing tank 5, peristaltic pump 6 and foamer 7, and their components are all products in the prior art.

[0045] The inlet and outlet ends of the flow regulating device 8 are each equipped with a sealing ring. In the above scheme, the sealing rings (not shown in the figure) at the inlet and outlet ends of the flow regulating device 8 prevent leakage through gaps, ensuring that all water flow participates in regulation through the annular flow channel, and avoiding non-regulating leakage from interfering with flow stability. The elastic sealing characteristics of the sealing ring can also compensate for minor tolerances in the connection between the valve body 81 and the pipeline, reducing the assembly precision requirements, while preventing corrosive media in humid environments from seeping into the interior of the valve body 81, thus improving the waterproof performance and service life of the entire system.

[0046] The through-hole 831 is a single water hole opened along the central axis of the limiting seat 83. In the above scheme, the single water hole design along the central axis of the limiting seat 83 simplifies the manufacturing process, eliminating the need for complex circumferential drilling and positioning, and reducing manufacturing costs by 15%. The axial layout of the single water hole allows water to flow along the central axis of the valve body 81, reducing pressure loss caused by turbulence and lowering water flow resistance by 10% compared to the multi-water-hole scheme. It is especially suitable for small-flow foam shield systems with mechanical self-regulating flow devices, avoiding slow foam generation due to excessive resistance.

[0047] Preferably, the total flow area of ​​the through hole 831 is 48% to 60% of the cross-sectional area corresponding to the nominal diameter of the valve body 81, and the total flow area of ​​the through hole 831 is not less than 1.2 times the maximum cross-sectional area of ​​the annular flow channel. This ensures that the through hole 831 will not become a new throttling point due to its small area, avoiding a head loss exceeding 0.05 MPa, nor will it weaken the structural strength of the limit seat 83 due to its large area, preventing deformation of the limit seat 83 due to long-term water flow impact. This proportional range ensures that the pressure loss of water flowing through the limit seat 83 is stabilized at 0.03-0.05 MPa, matching the regulating capacity of the annular flow channel and ensuring pressure balance in the entire water system.

[0048] Work style:

[0049] After the system starts, the water in the water source pipeline 9 first enters the flow regulating device 8 through the inlet valve 3. At this time, the water flows along the inlet of the valve body 81 to the large-diameter end of the frustum-shaped valve core 82. When the tap water pressure is at a normal low pressure of 0.1MPa, the frustum-shaped valve core 82 maintains its initial position under the preload of the compression spring 84. The annular flow channel formed by its large-diameter end and the inner wall of the valve body 81 is at its maximum cross-sectional area. The resistance is small when the water flows through the annular flow channel, ensuring that the basic flow rate enters the switching valve 4 stably.

[0050] If the water pressure rises to 0.8 MPa due to fluctuations in the pipeline network, the thrust of the water flow on the large-diameter end of the frustum-shaped valve core 82 increases, overcoming the elastic force of the compression spring 84 and pushing the valve core to slide axially towards the limiting seat 83. During this process, the cross-sectional area of ​​the annular flow channel formed by the conical surface of the frustum-shaped valve core 82 and the inner wall of the valve body 81 decreases linearly with the displacement of the valve core. By reducing the flow area, the effect of the increased water pressure is offset, keeping the amount of water entering the switching valve 4 constant. When the water pressure drops, the rebound force of the compression spring 84 pushes the valve core to reset, and the cross-sectional area of ​​the annular flow channel increases accordingly, compensating for water loss and always maintaining a stable amount of water entering the chemical mixing tank 5.

[0051] A stable flow of water enters the chemical mixing tank 5 through the switching valve 4, where it is thoroughly mixed with the foam liquid flowing in from the foam storage tank 2 through the inlet according to a preset ratio. The mixture then enters the foam generator 7, forming fine foam with an air content of 70%-90%. If further optimization of the foam concentration is required, a peristaltic pump 6 uses the outlet of the chemical mixing tank 5 to mix a portion of the mixture with the foam output from the foam storage tank in a secondary ratio. Finally, the foam layer output by the foam generator 7 evenly covers the toilet bowl surface with a thickness of 3-8 cm, forming a complete foam shield. Throughout the entire operation, the flow regulation device 8 achieves full self-regulation through mechanical force balance, without the need for electrical control components. It can stably output foam that meets the requirements within a water pressure range of 0.1-0.8 MPa, adapting to the long-term use needs of the humid environment of the bathroom.

[0052] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A foam shield system with a mechanical self-regulating flow device, characterized in that Includes a base (1), a foam storage tank (2), a water inlet valve (3), a switching valve (4), a medicine mixing tank (5), a peristaltic pump (6), a foamer (7), and a flow regulating device (8) integrated on the base (1); The flow regulating device (8) includes a valve body (81) with water inlets at both ends. A frustum-shaped valve core (82) that can slide axially is provided in the inner cavity of the valve body (81). The large-diameter end of the frustum-shaped valve core (82) faces the water inlet direction of the valve body (81), and the small-diameter end faces the water outlet direction of the valve body (81). An annular flow channel is formed between the frustum-shaped valve core (82) and the inner cavity of the valve body (81). The valve body (81) has a limiting seat (83) at the water outlet end. The limiting seat (83) has several compression springs (84) at one end facing the frustum-shaped valve core (82). The end of the compression springs (84) away from the limiting seat (83) is connected to the frustum-shaped valve core (82) through a connecting plate (85). The limiting seat (83) has a through hole (831) for water to flow through.

2. The foam shield system with mechanical self-regulating flow device of claim 1, wherein, The cone angle of the frustum-shaped valve core (82) is 25°-45°, and the large diameter end diameter of the frustum-shaped valve core (82) is 0.5-2mm smaller than the inner diameter of the valve body (81).

3. The foam shield system with mechanical self-regulating flow device of claim 1, wherein, The spring constant of the compression spring (84) is 1-5 N / mm, and the initial pre-compression is 3-8 mm.

4. The foam shield system with mechanical self-regulating flow device of claim 1, wherein, The number of compression springs (84) is four, and the compression springs (84) are arranged in a ring array around the central axis of the limiting seat (83).

5. The foam shield system with mechanical self-regulating flow device of claim 4, wherein, A guide rod (86) is inserted through the center hole of the compression spring (84). A guide hole is provided in the limiting seat (83) for the guide rod (86) to slide. One end of the guide rod (86) is fixedly connected to the connecting plate (85), and the other end of the guide rod (86) is slidably connected to the guide hole.

6. The foam shield system with mechanical self-regulating flow device of claim 1, wherein, One end of the inlet valve (3) is connected to the water source pipeline (9), and the other end is connected to the flow regulating device (8). The outlet of the flow regulating device (8) is connected to the inlet of the switching valve (4). The outlet of the switching valve (4) is connected to the inlet of the medicine mixing tank (5). The outlet of the medicine mixing tank (5) is connected to the foamer (7). The outlet of the foam storage tank (2) is connected to the air inlet of the peristaltic pump (6). The air outlet of the peristaltic pump (6) is connected to the medicine inlet of the medicine mixing tank (5).

7. The foam shield system with mechanical self-regulating flow device of claim 1, wherein, The total flow area of ​​the through hole (831) is 48% to 60% of the cross-sectional area corresponding to the nominal diameter of the valve body (81), and the total flow area of ​​the through hole (831) is not less than 1.2 times the maximum cross-sectional area of ​​the annular flow channel.

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