Flowmeter for drainage of non-full pipe flow

Abstract

The invention relates to the technical field of flow measurement, in particular to a flow meter for drainage of non-full pipe flow, which comprises a drainage tank, a measuring instrument and an ultrasonic liquid level meter electrically connected with the measuring instrument, the device further comprises a measuring groove, a gate structure, an inflation structure and a siphon type drainage pipe. A floating plate is arranged in the measuring groove. The siphon type drainage pipe is connected between the lower end of the measuring tank and the side end of the drainage tank; the flowmeter for drainage of the non-full pipe flow is designed on the basis of the communicating vessel principle, the air pressure cleaning principle and the siphonic effect, the flowmeter uses the principle of the communicating vessel liquid level and the like, water flow fluctuation is suppressed through the floating plate, and the accuracy of fluid liquid level height measurement can be improved; the flowmeter can clean the measuring groove based on the air pressure cleaning principle, siphonage can be generated through the design of the siphoning type drainage pipe, water can be rapidly drained, impurity sediments and the like in liquid are taken away, and the cleaning effect on the measuring groove is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of flow measurement, and particularly relates to a flowmeter for non-full pipe flow drainage. Background Art

[0002] In industrial production, drainage flowmeters are even more indispensable. For example, in industries such as chemical engineering and pharmaceuticals, accurate drainage flow monitoring is the cornerstone of production safety and compliant operation. It provides real-time feedback on the drainage situation, helps enterprises optimize the process flow, avoid resource waste, and ensure a green, efficient, and orderly production process. In industrial open drainage systems, non-full pipe flow is a common flow state. Due to the complex flow state of non-full pipe flow, traditional full pipe flowmeters are difficult to accurately measure its flow rate.

[0003] Currently, in industry, an ultrasonic level gauge is used to directly measure the liquid level height and then calculate the flow rate value. The specific steps include: 1) Using an ultrasonic level gauge to measure the liquid level height in the drainage tank; 2) Determining the bottom width of the drainage tank and the height from the liquid surface to the bottom of the channel; 3) Calculating the cross-sectional area of the drainage tank; 4) Calculating the wetted perimeter, that is, calculating the perimeter of the liquid in contact with the wall of the drainage tank; 5) Calculating the hydraulic radius, that is, calculating the ratio of the cross-sectional area of flow to the wetted perimeter; 6) Using the Manning formula to calculate the flow velocity of the drainage tank; 7) Calculating the flow rate, that is, calculating the product of the cross-sectional area of flow and the flow velocity.

[0004] The publicly disclosed Chinese patent with the publication number CN112504366A discloses a non-full pipe electromagnetic flowmeter installed at the first fixed end and the second fixed end on the inner wall of an open channel. It includes: a bidirectional telescopic rod horizontally arranged on the inner wall of the open channel and placed perpendicular to the water flow direction, with movable ends provided at both ends of the bidirectional telescopic rod, and the two ends of the bidirectional telescopic rod are respectively fixedly connected to the first fixed end and the second fixed end; a second telescopic rod fixed to the lower end of the bidirectional telescopic rod; an external display device fixedly installed at the upper end of the bidirectional telescopic rod. A controller and a converter are installed in the external display device, and a display module is embedded at the outer end of the external display device, and the display module is electrically connected to the micro-control module; and an electromagnetic flowmeter body electrically connected to the external display device through a connecting wire, and the electromagnetic flowmeter body is fixedly connected to the movable end of the second telescopic rod. The publicly disclosed Chinese patent with the publication number CN102879045A discloses a non-full pipe ultrasonic flowmeter, including a single-chip microcomputer, a switching control circuit, a measurement circuit, and sensors installed at the bottom of the pipeline. The sensors include multiple groups of ultrasonic flow sensors for measuring flow velocity and an ultrasonic level transmitter. The ultrasonic flow sensors are connected to the single-chip microcomputer through the switching control circuit, the measurement circuit is respectively connected to the switching control circuit and the single-chip microcomputer, and the ultrasonic level transmitter is directly connected to the single-chip microcomputer.

[0005] The above-mentioned disclosed patents use electromagnetic technology or ultrasonic technology for measurement. However, in the actual measurement process, due to the surges or fluctuations in the draining water in the flowing state, when using electromagnetic technology or ultrasonic technology to measure and locate the liquid level height, it is affected by the surges or fluctuations, and the measured drainage volume is often much larger than the actual water consumption. Therefore, there is a problem of inaccurate measurement of the drainage volume. Summary of the Invention

[0006] In view of the above-mentioned disadvantages of the prior art, the present invention provides a flowmeter for non-full pipe flow drainage. By setting a measurement tank, the measurement tank and the drainage tank can form a controllable connection based on the principle of equal liquid levels in a communicating vessel through the lifting of a gate; during measurement, the gate is opened, and the liquid in the drainage tank enters the measurement tank. The floating plate provided in the measurement tank can rise with the rise of the liquid level. After the liquid levels are equal, the gate is closed. The floating plate can suppress the water flow fluctuations and make the liquid level tend to be stable. At this time, the ultrasonic level gauge can accurately measure the distance between itself and the floating plate, and then accurately measure the liquid level height by subtracting the measured distance and the thickness of the floating plate, effectively improving the measurement accuracy of the flow rate of non-full pipe flow drainage, and can solve the problem of inaccurate measurement of the drainage volume in the prior art when directly measuring the liquid level height by using an ultrasonic level gauge affected by fluid surges or fluctuations; in addition, the present invention is also provided with an inflation structure and a siphon drain pipe. After the measurement is completed, the inflation structure can inflate the airbag provided at the upper end of the floating plate to make its edge expand and touch the inner wall of the measurement tank, forming a sealed cavity; the inflation structure simultaneously injects high-pressure gas into the liquid to increase the pressure of the liquid. Since the liquid is incompressible, the pressure will be evenly and simultaneously transmitted upward and downward. At this time, the floating plate and the liquid level are in a sealed state. The upward transmitted pressure can lift the floating plate until it touches the L-shaped mounting seat; the downward transmitted pressure can press the liquid into the siphon drain pipe and then drain it into the drainage tank to enter the post-treatment process together, realizing the effect of cleaning the measurement tank and facilitating subsequent repeated measurement and use; when the siphon drain pipe is working, a negative pressure will be formed in the pipeline, thus generating a siphon phenomenon. This siphon effect can make the liquid flow rapidly in the pipeline, greatly improving the drainage capacity, and at the same time taking away the impurity deposits in the liquid during drainage, improving the cleaning effect on the measurement tank.

[0007] To achieve the above object and other related objects, the present invention provides a flowmeter for non-full pipe flow drainage, including a drainage tank, a measuring instrument, and an ultrasonic level gauge electrically connected to the measuring instrument; it further includes:

[0008] A measurement tank, the measurement tank is connected to one side of the drainage tank, a floating plate is provided in the measurement tank, and the ultrasonic level gauge is installed directly above the floating plate;

[0009] A gate structure, the gate structure uses a single gate, and the gate is installed at the side end of the drainage tank in a liftable manner for forming a partition between the drainage tank and the measurement tank;

[0010] An inflatable structure, the inflatable structure comprising an air pump and an airbag, the airbag being provided at the upper end of the floating plate; an air outlet port of the air pump is simultaneously connected to a first air pipe and a second air pipe, the first air pipe is connected to the airbag, and the second air pipe is connected to the measurement tank.

[0011] In an embodiment of the present invention, the gate structure includes:

[0012] A driving motor;

[0013] A pair of meshing and driving gears, one of the gears being sleeved on the output end of the driving motor;

[0014] An eccentric wheel, the eccentric wheel being mounted on the other gear;

[0015] A lifting rod rotatably hinged to the eccentric wheel, the gate being connected to the lifting rod.

[0016] In an embodiment of the present invention, sliding grooves are respectively provided at both side ends of the gate, and sliders slidably engaged with the corresponding sliding grooves are provided at the side ends of the drainage tank.

[0017] In an embodiment of the present invention, an L-shaped mounting seat is provided at the upper end of the measurement tank, the driving motor, the air pump, and the ultrasonic liquid level gauge are all mounted on the bottom plate of the L-shaped mounting seat, and a pair of meshing and driving gears are both mounted on the side plate of the L-shaped mounting seat through rotating connectors.

[0018] In an embodiment of the present invention, at least two symmetrically distributed pads are provided at the inner lower end of the measurement tank for supporting and giving the floating plate an initial height.

[0019] In an embodiment of the present invention, a siphon drain pipe is connected between the lower end of the measurement tank and the side end of the drainage tank. There is a low-level section and a high-level section on the siphon drain pipe. The liquid level of the low-level section is lower than the lowest liquid level of the measurement tank, and the liquid level of the high-level section is not lower than the maximum height of the drainage tank.

[0020] In an embodiment of the present invention, a first electric control valve is provided at one end of the siphon drain pipe for connecting to the measurement tank.

[0021] In an embodiment of the present invention, the first air pipe is a flexible pipe, and a second electric control valve is provided on the first air pipe.

[0022] In an embodiment of the present invention, the output end of the second air pipe is connected to the side end near the bottom of the measurement tank, and a third electric control valve is provided at the lower end of the second air pipe.

[0023] As described above, the flowmeter for non-full pipe flow drainage of the present invention has the following beneficial effects:

[0024] 1. By setting up a measuring groove, based on the principle of equal liquid levels in a communicating vessel, a controllable connection can be formed between the measuring groove and the drainage groove through the lifting of the gate. During measurement, the gate is opened, and the liquid in the drainage groove enters the measuring groove. The floating plate installed in the measuring groove can rise as the liquid level rises. After the liquid levels are equal, the gate is closed. The floating plate can suppress the water flow fluctuations, making the liquid level tend to be stable. At this time, an ultrasonic level gauge can accurately measure the distance between itself and the floating plate, and then accurately measure the liquid level height by subtracting the measured distance and the thickness of the floating plate, effectively improving the flow measurement accuracy for non-full pipe flow drainage.

[0025] 2. By setting up an inflation structure, after the measurement is completed, the inflation structure can inflate the airbag installed at the upper end of the floating plate to make its edge expand and touch the inner wall of the measuring groove, forming a sealed cavity. The inflation structure simultaneously introduces high-pressure gas into the liquid to increase the liquid pressure. Since the liquid is incompressible, the pressure will be transmitted evenly and simultaneously upward and downward. At this time, the floating plate and the liquid level are in a sealed state. The upward transmitted pressure can lift the floating plate until it touches the L-shaped mounting seat. The downward transmitted pressure can press the liquid into the siphon drain pipe and then drain it into the drainage groove and enter the post-treatment process together, achieving the effect of cleaning the measuring groove and facilitating subsequent repeated measurements.

[0026] 3. By setting up a siphon drain pipe, a negative pressure will be formed inside the pipe during the operation of the siphon drain pipe, thus generating a siphon phenomenon. This siphon effect can make the liquid flow rapidly inside the pipe, greatly improving the drainage capacity, and at the same time taking away the impurity deposits in the liquid during drainage, improving the cleaning effect on the measuring groove.

[0027] 4. By setting up a gate structure, the gate structure provides driving force through a driving motor, cooperates with a gear for transmission, drives an eccentric wheel to rotate, and makes the gate connected to the lifting rod rise and fall to control the connection between the drainage groove and the measuring groove. The lifting distance of the eccentric wheel is short, which can achieve rapid lifting without affecting the principle of the communicating vessel, facilitating repeated measurements.

[0028] 5. The present invention is a flowmeter for non-full pipe flow drainage designed based on the principles of communicating vessels, air pressure cleaning, and siphon effect. This flowmeter can ensure that the fluid liquid levels in the drainage groove are equally connected to the measuring groove based on the principle of equal liquid levels in a communicating vessel. By suppressing the water flow fluctuations with a floating plate, it improves the accuracy of measuring the fluid liquid level height. After the measurement is completed, based on the air pressure cleaning principle, this flowmeter can use gas pressure to squeeze and drain the liquid while cleaning the measuring groove, facilitating subsequent repeated measurements. The design of the siphon drain pipe can generate a siphon phenomenon to drain water rapidly and take away the impurity deposits in the liquid, improving the cleaning effect on the measuring groove. Description of the Drawings

[0029] Figure 1It shows a schematic diagram of the overall structure of the flowmeter for non-full pipe flow drainage disclosed by the present invention.

[0030] Figure 2 It shows a schematic diagram of the overall structure of another perspective of the flowmeter for non-full pipe flow drainage disclosed by the present invention.

[0031] Figure 3 It shows a schematic exploded view of the flowmeter for non-full pipe flow drainage disclosed by the present invention with the drainage groove removed.

[0032] Figure 4 It shows a schematic exploded view of another perspective of the flowmeter for non-full pipe flow drainage disclosed by the present invention with the drainage groove removed.

[0033] Description of component numbers

[0034] Drainage groove 1; slider 11; measuring instrument 2; ultrasonic level gauge 3; third electric control valve 4; measuring tank 5; backing plate 51; floating plate 6; gate structure 7; gate 71; chute 711; drive motor 72; gear 73; eccentric wheel 74; lifting rod 75; inflating structure 8; air pump 81; airbag 82; first air pipe 83; second air pipe 84; siphon drainage pipe 9; low-level section 91; high-level section 92; L-shaped mounting seat 10; first electric control valve 12; second electric control valve 13. Specific implementation manners

[0035] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0036] Please refer to Figures 1 to 4 . It should be noted that the structures, ratios, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in the art to understand and read, and are not used to limit the limiting conditions under which the present invention can be implemented. Therefore, they do not have technical essential significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope that can be covered by the technical content disclosed by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in this specification are only for the convenience of clear description and are not used to limit the scope under which the present invention can be implemented. The change or adjustment of their relative relationships, without substantial change in the technical content, should also be regarded as the scope under which the present invention can be implemented.

[0037] Please refer to Figures 1 - 4, the present invention provides a flowmeter for non-full pipe flow drainage, comprising a drainage trough 1, a measuring instrument 2, and an ultrasonic level gauge 3 electrically connected to the measuring instrument 2; further comprising a measuring trough 5, a gate structure 7, an inflation structure 8, and a siphon drain pipe 9.

[0038] The measuring trough 5 communicates with one side of the drainage trough 1. A floating plate 6 is provided in the measuring trough 5. The floating plate 6 is made of a metal material, a PP material, or a PTFE material. The floating plate 6 has good buoyancy. When the fluid level height in the measuring trough 5 changes, the floating plate 6 will move accordingly and remain floating on the upper end of the liquid surface. The ultrasonic level gauge 3 is installed directly above the floating plate 6 for measuring the distance from the ultrasonic level gauge 3 itself to the upper part of the floating plate 6. At least two symmetrically distributed pads 51 are provided at the lower end inside the measuring trough 5 for supporting and giving the floating plate 6 an initial height.

[0039] The gate structure 7 includes a gate 71, a driving motor 72, a pair of meshing gears 73, an eccentric wheel 74, and a lifting rod 75. One of the gears 73 is sleeved on the output end of the driving motor 72, the eccentric wheel 74 is installed on the other gear 73, the lifting rod 75 is rotatably hinged to the eccentric wheel 74, and the gate 71 is connected to the lifting rod 75; by providing a driving force through the driving motor 72, the pair of meshing gears 73 mesh and rotate, driving the eccentric wheel 74 to rotate, and further driving the lifting rod 75 rotatably hinged to the eccentric wheel 74 to move up and down; sliding grooves 711 are respectively provided at both side ends of the gate 71, and sliding blocks 11 corresponding to the sliding grooves 711 are provided at the side end of the drainage trough 1; the gate 71 is liftably fitted to the side end of the drainage trough 1 to form a partition between the drainage trough 1 and the measuring trough 5.

[0040] Based on the principle of equal liquid levels in a communicating vessel, the present invention can form a controllable connection between the measuring trough 5 and the drainage trough 1 through the lifting of the gate 71; during measurement, the gate 71 is opened, and the liquid in the drainage trough 1 enters the measuring trough 5. The floating plate 6 provided in the measuring trough 5 can rise with the rise of the liquid surface. After the liquid levels are equal, the gate is closed. The floating plate 6 can suppress the water flow fluctuations and make the liquid surface tend to be stable. At this time, the ultrasonic level gauge 3 can accurately measure the distance from itself to the floating plate 6, and then accurately measure the liquid level height by subtracting the measured distance and the thickness of the floating plate 6, effectively improving the flow measurement accuracy for non-full pipe flow drainage; in specific implementation, the gate 71 can be lifted and lowered multiple times to measure the drainage liquid level heights at different times, and taking the average liquid level height can further improve the flow measurement accuracy for non-full pipe flow drainage.

[0041] The inflatable structure 8 includes an air pump 81 and an airbag 82. The airbag 82 is arranged at the upper end of the floating plate 6. To cooperate with the inflation of the airbag 85, the shapes of both the airbag 82 and the floating plate 6 are the same as the inner cavity shape of the measuring groove 5. The area of the floating plate 6 is set to be approximately four-fifths of the horizontal area of the inner cavity of the measuring groove 5, and the area of the airbag 82 is slightly larger than that of the floating plate 6. When inflated, the edge of the airbag 82 can quickly expand and contact the inner wall of the measuring groove 5. The air outlet port of the air pump 81 is simultaneously connected to a first air pipe 83 and a second air pipe 84. The first air pipe 83 is connected to the airbag 82, and the second air pipe 84 is connected to the measuring groove 5. The first air pipe 83 is a flexible pipe with a small weight and flexibility. It neither affects the floating performance of the floating plate 6 nor can bend synchronously with the floating movement of the floating plate 6. A second electric control valve 13 is provided on this flexible pipe to control the inflation connection of the first air pipe 83. The output end of the second air pipe 84 is connected to the side end of the measuring groove 5 near the bottom. A third electric control valve 4 is provided at the lower end of the second air pipe 84 to control the inflation connection of the second air pipe 84.

[0042] The siphon drain pipe 9 is connected between the lower end of the measuring groove 5 and the side end of the drain tank 1. After the measurement is completed, the inflatable structure can inflate the airbag 82 arranged at the upper end of the floating plate 6 to make its edge expand and touch the inner wall of the measuring groove 5, forming a sealed cavity. The inflatable structure simultaneously injects high-pressure gas into the liquid to increase the pressure of the liquid. Since the liquid is incompressible, the pressure will be transmitted evenly and simultaneously upward and downward. At this time, the floating plate 6 and the liquid surface are in a sealed state. The upward transmitted pressure can lift the floating plate 6 until it touches the L-shaped mounting seat 10 and is limited. The downward transmitted pressure can press the liquid into the siphon drain pipe 9 and then drain it into the drain tank 1 and enter the post-treatment process together, achieving the effect of cleaning the measuring groove 5 and facilitating subsequent repeated measurements.

[0043] There is a low-level section 91 and a high-level section 92 on the siphon drain pipe 9. The liquid level of the low-level section 91 is lower than the lowest liquid level of the measuring groove 5, and the liquid level of the high-level section 92 is not lower than the maximum height of the drain tank 1. The cooperation of the low-level section 91 and the high-level section 92 can form a pressure difference. When the siphon drain pipe 9 is working, a negative pressure will be formed inside the pipe, thus generating a siphon phenomenon. This siphon effect can make the liquid flow rapidly in the pipe, greatly improving the drainage capacity, and at the same time taking away the impurity deposits in the liquid during drainage, improving the cleaning effect on the measuring groove. One end of the siphon drain pipe 9 for connecting the measuring groove 5 is provided with a first electric control valve 12 to control the on-off of the siphon drain pipe 9.

[0044] After accurately measuring the liquid level height in the drain tank 1, the specific calculation steps and formulas of the present invention are as follows:

[0045] 1) Use an ultrasonic level gauge 3 to measure the height from itself to the floating plate, denoted as h1; know or measure the thickness of the floating plate with a tool ruler, denoted as h2; know or measure the height of the drainage trough 1 with a tool ruler, denoted as h3; calculate h3 - h2 - h1 = h to obtain the liquid level height h in the drainage trough;

[0046] 2) Know or measure the bottom width b of the drainage trough 1 with a tool ruler;

[0047] 3) Calculate the cross-sectional area A of the drainage trough 1, and the calculation formula is A = b·h;

[0048] 4) Calculate the wetted perimeter P, that is, calculate the perimeter where the liquid contacts the inner wall of the drainage trough 1, and the calculation formula is P = b + 2h;

[0049] 5) Calculate the hydraulic radius R, that is, calculate the ratio of the cross-sectional area of flow to the wetted perimeter, and the calculation formula is Substitute A and P into

[0050] 6) Use the Manning formula to calculate the flow velocity υ of the drainage trough 1, and the calculation formula is In the formula, n is the Manning roughness coefficient (related to the material of the drainage trough 1, which can be obtained by looking up the table. For example, for a concrete channel, n≈0.013, and for an earthen channel, n≈0.025), and S is the hydraulic gradient (the bottom slope of the drainage trough 1, dimensionless);

[0051] 7) Calculate the flow rate Q, that is, calculate the product of the cross-sectional area of flow and the flow velocity, and the calculation formula is Q = A·υ.

[0052] For example, given that the bottom width b of the drainage trough 1 is 2m, the measured liquid level height h is 0.5m, the Manning roughness coefficient n is 0.025, and the hydraulic gradient S is 0.001, calculate the cross-sectional area of flow A = b·h = 2×0.5 = 1m 2 ; calculate the wetted perimeter P = b + 2h = 2 + 2×0.5 = 3m; calculate the hydraulic radius Calculate the flow velocity Calculate the flow rate Q = A·υ = 1×0.061 = 0.61m 3 / s.

[0053] In summary, the present invention is a flowmeter for non-full pipe flow drainage designed based on the principle of communicating vessels, the principle of air pressure cleaning, and the siphon effect. This flowmeter can ensure that the fluid levels in the drainage tank 1 are equal and are connected to the measurement tank 5 by using the principle of equal liquid levels in the communicating vessels. By suppressing the water flow fluctuations with the floating plate 6, the accuracy of measuring the fluid level height is improved; after the measurement is completed, based on the principle of air pressure cleaning, this flowmeter can not only squeeze out the liquid by using gas pressure but also clean the measurement tank, facilitating subsequent repeated measurements; the design of the siphon drain pipe 9 can generate a siphon phenomenon to quickly drain water and carry away impurity deposits in the liquid, improving the cleaning effect on the measurement tank. Therefore, the present invention effectively overcomes various drawbacks in the prior art and has high industrial utilization value.

[0054] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A flowmeter for non-full pipe flow drainage, comprising a drainage trough (1), a measuring instrument (2), and an ultrasonic level gauge (3) electrically connected to the measuring instrument (2); It is characterized in that It further includes: A measuring trough (5) which is communicated with one side of the drainage trough (1). A floating plate (6) is arranged in the measuring trough (5), and the ultrasonic level gauge (3) is installed directly above the floating plate (6); A gate structure (7) which uses a gate (71). The gate (71) is installed on the side end of the drainage trough (1) in a liftable manner for forming a partition between the drainage trough (1) and the measuring trough (5); An inflation structure (8) which includes an air pump (81) and an airbag (82). The airbag (82) is arranged at the upper end of the floating plate (6); The air outlet port of the air pump (81) is simultaneously connected with a first air pipe (83) and a second air pipe (84). The first air pipe (83) is connected to the airbag (82), and the second air pipe (84) is connected to the measuring trough (5).

2. The flowmeter for non-full pipe flow drainage according to claim 1, characterized in that, The gate structure (7) includes: A driving motor (72); A pair of meshing and driving gears (73), and one of the gears (73) is sleeved on the output end of the driving motor (72); An eccentric wheel (74) which is installed on the other gear (73); A lifting rod (75) rotatably hinged on the eccentric wheel (74), and the gate (71) is connected to the lifting rod (75).

3. The flowmeter for non-full pipe flow drainage according to claim 2, wherein: Chute grooves (711) are respectively arranged at both side ends of the gate (71), and sliding blocks (11) which are in sliding fit with the corresponding chute grooves (711) are arranged at the side end of the drainage trough (1).

4. The flowmeter for non-full pipe flow drainage according to claim 3, characterized in that: An L-shaped mounting seat (10) is arranged at the upper end of the measuring trough (5). The driving motor (72), the air pump (81), and the ultrasonic level gauge (3) are all installed on the bottom plate of the L-shaped mounting seat (10), and a pair of meshing and driving gears (73) are all installed on the side plate of the L-shaped mounting seat (10) through rotating connectors.

5. The flowmeter for non-full flow drainage according to claim 1, wherein: At least two symmetrically distributed cushion blocks (51) are arranged at the inner lower end of the measuring trough (5) for supporting and giving the floating plate (6) an initial height.

6. The flowmeter for non-full flow drainage according to claim 1, characterized in that: A siphon drainage pipe (9) is connected between the lower end of the measuring trough (5) and the side end of the drainage trough (1). There is a low-level section (91) and a high-level section (92) on the siphon drainage pipe (9). The liquid level of the low-level section (91) is lower than the lowest liquid level of the measuring trough (5), and the liquid level of the high-level section (92) is not lower than the maximum height of the drainage trough (1).

7. The flowmeter for non-full flow drainage according to claim 6, wherein: A first electric control valve (12) is arranged at one end of the siphon drainage pipe (9) for connecting the measuring trough (5).

8. The flowmeter for non-full pipe flow drainage according to claim 1, wherein: The first air pipe (83) is a flexible pipe, and a second electric control valve (13) is arranged on the first air pipe (83).

9. The flowmeter for non-full flow drainage according to claim 8, wherein: The output end of the second air pipe (84) is connected to the side end of the measuring trough (5) close to the bottom, and a third electric control valve (4) is arranged at the lower end of the second air pipe (84).

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