An electromagnetic flowmeter

Abstract

The present invention discloses an electromagnetic flowmeter, including a flow tube and an instrument head. The inlet end of the flow tube is set as a gradient tube, and the inner top surface of the gradient tube is sloped. The flowmeter also includes: a temperature difference block, which is set on the sloped inner top surface of the gradient tube, and a heating wire is set on the surface wall facing the inner part of the gradient tube; an exhaust assembly, which is set at the upper end of the gradient tube, and an interactive port is set at the lower end thereof and corresponds to the highest position of the temperature difference block, and is used to collect gas mixed in the flowing liquid in the flow tube and discharge it to the outside. By setting the gradient tube, the present invention can guide the fluid from the larger inner diameter pipeline into the smaller inner diameter flow tube, ensuring that the straight pipe section at the flow tube is full of flow, and under the setting of the temperature difference block, the pressure difference between the inside and outside of the bubble is caused to break, and the gas generated enters the interactive port and is discharged to the outside through the exhaust assembly, ensuring that the fluid flowing through the straight pipe section of the flow tube does not contain bubbles, and ensuring the detection accuracy of the flowmeter.

Description

Technical Field

[0001] The present invention relates to the technical field of flowmeters, and in particular to an electromagnetic flowmeter. Background Art

[0002] The electromagnetic flowmeter is a new type of flow measuring instrument that uses the principle of electromagnetic induction to measure the flow of conductive fluid based on the electromotive force induced when the conductive fluid passes through an external magnetic field, and directly forms a digital display on the instrument. Existing electromagnetic flowmeters can basically meet daily usage needs, but there are still some shortcomings that need to be improved.

[0003] Patent document CN210464567U disclosed an electromagnetic flowmeter on May 5, 2020. The measuring tube includes a contraction section, a straight tube section, and a diffusion section connected in sequence. The contraction section and the diffusion section are asymmetric tapered tubes, located on the same horizontal plane as the straight tube section and the bottom of the fluid pipeline. Two detection electrodes are symmetrically and detachably arranged on the front and rear sides of the straight tube section, and close to the lower half of the straight tube section. A liquid level gauge is also provided at the end of the straight tube section. The detection electrode includes a threaded rod and a head. The detection electrode is installed on the measuring tube through the boss of the rod and the step hole. A sealing ring, a sealing ring, and a compression spring structure are provided between the measuring tube and the detection electrode. The utility model keeps the fluid in a full or nearly full state, improving the accuracy of the measurement results. The detection electrode can be directly installed and removed without having to disassemble the entire measuring tube, which facilitates cleaning, maintenance, and replacement of the electrode, improves the maintainability of the equipment, and ensures sealing.

[0004] As in the prior art of the above patent, the fluid in the straight pipe section cannot fill the pipe or there are many bubbles mixed in the fluid, which can easily cause large measurement errors. Therefore, an electromagnetic flowmeter is urgently needed to solve the above problems. Summary of the Invention

[0005] The object of the present invention is to provide an electromagnetic flowmeter to solve the above-mentioned deficiencies in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] An electromagnetic flowmeter includes a flow tube and an instrument head arranged on the flow tube, wherein the inlet end of the flow tube is arranged as a gradient tube, the inner top surface of the gradient tube is sloped, and is arranged to continuously descend along the fluid guide height set in the flow tube. The electromagnetic flowmeter also includes: a temperature difference block, which is arranged on the sloped inner top surface of the gradient tube and has a heating wire on its surface wall facing the interior of the gradient tube; an exhaust assembly, which is arranged at the upper end of the gradient tube and has an interactive port at its lower end corresponding to the highest position of the temperature difference block, and is used to collect gas mixed in the flowing liquid in the flow tube and discharge it to the outside.

[0008] Preferably, a temperature control chamber is provided at the upper end of the gradient tube, a temperature control unit is provided in the temperature control chamber, and the temperature control unit is electrically connected to the heating wire.

[0009] Preferably, the exhaust assembly includes an interactive tube fixedly arranged at the upper end of the gradient tube, the interactive port is arranged at the lower end of the interactive tube, and an exhaust head is arranged at the upper end of the side wall of the interactive tube.

[0010] Preferably, a float is movably provided in the interactive tube, and a switch assembly is provided in the exhaust head. The switch assembly is linked with the float. When the float falls freely, the switch assembly controls the exhaust head to open, and when the float floats up due to the buoyancy of the fluid, the switch assembly controls the exhaust head to close.

[0011] Preferably, the switch assembly includes a contraction cavity provided in the exhaust head, an exhaust hole connected to the contraction cavity provided at the end of the exhaust head, a ball plug movably provided in the contraction cavity, an end of the ball plug away from the exhaust hole is fixedly connected to a pull rod, an end of the pull rod away from the ball plug is connected to the inner wall of the interaction tube through an elastic member, and the movement of the pull rod is linked to the lifting and lowering of the floating block.

[0012] Preferably, a push rod is fixedly provided on the upper end of the float, and the push rod is movably connected to the end of the pull rod away from the ball plug through a hinged connecting rod.

[0013] Preferably, a through hole is provided at the connection between the interactive tube and the exhaust head, and the pull rod is provided in a cross rod shape and movably passes through the through hole.

[0014] Preferably, a columnar electrode is provided on the side direction of the inner wall of the flow tube, the temperature difference block is rotatably provided in the gradient tube, and a reciprocating component for driving the temperature difference block to rotate is provided on the gradient tube. The temperature difference block guides the fluid flowing from the gradient tube into the flow tube to the upper and lower cutting directions of the columnar electrode at both ends of the rotation range.

[0015] Preferably, the reciprocating component includes a movable warehouse fixed on the gradient tube, a swinging piece is elastically rotatably provided in the movable warehouse, the upper end of the swinging piece extends out of the movable warehouse and reaches a position to block the exhaust hole, a cam is rotatably provided in the movable warehouse, the swinging piece is linked to the cam through a one-way transmission component, and a lifting rod is provided on the lower side of the cam for lifting and lowering movement, and the lower end of the lifting rod is movably connected to the temperature difference block.

[0016] Preferably, the one-way transmission assembly includes a rotary block coaxially connected to the rotating shaft of the swing member, a pawl is elastically provided on the outer wall of the rotary block, a ratchet matching the pawl is sleeved on the outer side of the rotary block, and the ratchet is rotatably set in the movable bin and connected to the cam through gear transmission.

[0017] In the above technical solution, the beneficial effects of the present invention are:

[0018] The electromagnetic flowmeter is provided with a gradient tube, which can guide the fluid from the larger inner diameter pipeline into the smaller inner diameter flow tube, ensuring that the straight pipe section at the flow tube is full of flow. Moreover, under the setting of the temperature difference block, the bubbles existing in the upper layer of the fluid entering the gradient tube can flow along the sloped inner top surface of the gradient tube, thereby contacting the surface of the temperature difference block heated by the heating wire, causing the pressure difference between the inside and outside of the bubbles to burst, and the generated gas then gathers to the uppermost layer of the fluid, thereby smoothly entering the interactive port and being discharged to the outside through the exhaust component, thereby ensuring that the fluid flowing through the straight pipe section of the flow tube does not contain bubbles, and ensuring the detection accuracy of the flowmeter.

[0019] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0020] This application document provides an overview of various implementations or examples of the technology described in this disclosure, and is not a comprehensive disclosure of the full scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0022] Figure 1 A schematic diagram of the overall structure provided by an embodiment of the present invention;

[0023] Figure 2 A schematic diagram of a front cross-sectional structure provided by an embodiment of the present invention;

[0024] Figure 3 The embodiment of the present invention provides Figure 2 Schematic diagram of the enlarged structure at A in the middle;

[0025] Figure 4 A schematic diagram of the internal structure of an interactive tube provided in an embodiment of the present invention;

[0026] Figure 5 A schematic structural diagram of a one-way transmission assembly provided in an embodiment of the present invention.

[0027] Description of reference numerals:

[0028] 1. Flow tube; 2. Instrument head; 3. Gradient tube; 4. Temperature difference block; 5. Heating wire; 6. Interactive port; 7. Temperature control chamber; 8. Temperature control unit; 9. Interactive tube; 10. Exhaust head; 11. Float; 12. Shrinkage chamber; 13. Exhaust hole; 14. Ball plug; 15. Pull rod; 16. Elastic part; 17. Push rod; 18. Connecting rod; 19. Through hole; 20. Columnar electrode; 21. Movable chamber; 22. Swinging part; 23. Cam; 24. Up and down rod; 25. Rotary block; 26. Pawl; 27. Ratchet. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0030] See also Figure 1-5 An electromagnetic flowmeter provided by an embodiment of the present invention includes a flow tube 1 and an instrument head 2 arranged on the flow tube 1. The inlet end of the flow tube 1 is set as a gradient tube 3. The inner top surface of the gradient tube 3 is sloped and is continuously descending along the fluid guide height set in the flow tube 1. The electromagnetic flowmeter also includes: a temperature difference block 4, which is set on the sloped inner top surface of the gradient tube 3 and has a heating wire 5 on its surface wall facing the inside of the gradient tube 3; an exhaust component, which is set at the upper end of the gradient tube 3 and has an interactive port 6 at its lower end corresponding to the highest position of the temperature difference block 4, which is used to collect gas mixed in the flowing liquid in the flow tube 1 and discharge it to the outside.

[0031] Specifically, the flow tube 1 is a straight tube; the instrument head 2 integrates signal processing, calculation, display, communication, and power management functions, responsible for converting sensor signals into readable flow data and implementing system control. A connecting plate is provided at the end of the gradient tube 3 for connection to a monitoring pipeline, which has a connection port that matches the end of the gradient tube 3. The maximum cross-sectional flux of the gradient tube 3 is greater than the cross-sectional flux of the flow tube 1, and the cross-sectional flux of the gradient tube 3 decreases gradually from the end to the end connected to the flow tube 1 to match the cross-sectional flux of the flow tube 1. The temperature difference block 4 is arranged along the sloped inner top surface of the gradient tube 3. The temperature difference block 4 is made of a heat-conducting material, or at least the surface of the temperature difference block 4 facing the inside of the gradient tube 3 is heat-conducting. The heating wire 5 is used to heat the surface of the temperature difference block 4 facing the inside of the gradient tube 3 to a temperature higher than the temperature of the fluid flowing through the gradient tube 3. When bubbles floating in the upper layer of the fluid contact the surface of the temperature difference block 4, the bubbles are easily ruptured due to the internal and external temperature difference. The exhaust component is a passive structure. When the fluid entering the gradient tube 3 contains obvious gas, the gas can be introduced through the interactive port 6 and discharged to the outside. When the fluid entering the gradient tube 3 does not contain obvious gas, the interactive port 6 introduces part of the fluid, but does not discharge the fluid to the outside. In actual use, this technical solution can be used to introduce the fluid from the larger inner diameter pipeline into the smaller inner diameter flow tube 1 through the setting of the gradient tube 3, ensuring that the straight pipe section at the flow tube 1 is full of flow. Moreover, under the setting of the temperature difference block 4, the bubbles in the upper layer of the fluid entering the gradient tube 3 can flow along the sloped inner top surface of the gradient tube 3, thereby contacting the surface of the temperature difference block 4 heated by the heating wire 5, causing the pressure difference between the inside and outside of the bubbles to rupture, and the gas generated by the bubbles then gathers at the top layer of the fluid, thereby smoothly entering the interactive port 6 and being discharged to the outside through the exhaust component, ensuring that the fluid flowing through the straight pipe section of the flow tube 1 does not contain bubbles, and ensuring the detection accuracy of the flow meter.

[0032] Compared with the prior art, the electromagnetic flowmeter proposed in the embodiment of the present invention can guide the fluid from the larger inner diameter pipeline into the smaller inner diameter flow tube 1 by setting a gradient tube 3, ensuring that the straight pipe section at the flow tube 1 is full of flow, and under the setting of the temperature difference block 4, the bubbles in the upper layer of the fluid entering the gradient tube 3 can flow along the sloped inner top surface of the gradient tube 3, thereby contacting the surface of the temperature difference block 4 heated by the heating wire 5, causing the pressure difference between the inside and outside of the bubbles to burst, and the gas generated by it then gathers to the uppermost layer of the fluid, thereby smoothly entering the interactive port 6 and being discharged to the outside through the exhaust component, ensuring that the fluid flowing through the straight pipe section of the flow tube 1 does not contain bubbles, and ensuring the detection accuracy of the flowmeter.

[0033] As the preferred technical solution of this embodiment, a temperature control chamber 7 is provided at the upper end of the gradient tube 3, and a temperature control unit 8 is provided in the temperature control chamber 7. The temperature control unit 8 is electrically connected to the heating wire 5. Specifically, the temperature control unit 8 is used to control the heating wire 5 to maintain a certain safe temperature. A power supply can also be provided in the temperature control chamber 7. The power supply is preferably externally powered and is used to power the heating wire 5. This is existing technology and will not be elaborated on.

[0034] As the preferred technical solution of this embodiment, the exhaust assembly includes an interactive tube 9 fixedly arranged at the upper end of the gradient tube 3, an interactive port 6 is arranged at the lower end of the interactive tube 9, and an exhaust head 10 is arranged at the upper end of the side wall of the interactive tube 9. Specifically, the interior of the interactive tube 9 is connected to the interior of the gradient tube 3 through the interactive port 6. Under its own pressure, a part of the fluid in the gradient tube 3 can enter the interactive tube 9 through the interactive port 6. When there is gas in the fluid, the gas can also enter the interactive tube 9 through the interactive port 6 due to buoyancy, thereby causing the fluid level in the interactive tube 9 to drop; the exhaust head 10 corresponds to the upper end of the interactive tube 9 and is connected.

[0035] As a further preferred technical solution of this embodiment, a float 11 is movably disposed within the interaction tube 9, and a switch assembly is disposed within the exhaust head 10. The switch assembly and the float 11 are linked. When the float 11 is freely falling, the switch assembly controls the exhaust head 10 to open. When the float 11 is lifted by the buoyancy of the fluid, the switch assembly controls the exhaust head 10 to close. Specifically, the outer diameter of the float 11 is smaller than the inner diameter of the interaction tube 9, i.e., a gap is left between the side of the float 11 and the inner wall of the interaction tube 9 to facilitate gas passage. The linkage between the switch assembly and the float 11 enables the switch assembly to passively control the opening and closing of the exhaust head 10. When the float 11 is lifted within the interaction tube 9, i.e., the fluid level within the interaction tube 9 is high and little or no gas has entered the interaction tube 9, the corresponding switch assembly controls the exhaust head 10 to close. When the float 11 is lowered within the interaction tube 9, i.e., the fluid level within the interaction tube 9 is low and more gas has entered the interaction tube 9, the corresponding switch assembly controls the exhaust head 10 to open and discharge excess gas.

[0036] As a further preferred technical solution of this embodiment, the switch assembly includes a shrinkage cavity 12 arranged in the exhaust head 10, and an exhaust hole 13 connected to the shrinkage cavity 12 is provided at the end of the exhaust head 10. A ball plug 14 is movably provided in the shrinkage cavity 12, and the end of the ball plug 14 away from the exhaust hole 13 is fixedly connected to the pull rod 15, and the end of the pull rod 15 away from the ball plug 14 is connected to the inner wall of the interaction tube 9 through an elastic member 16. The movement of the pull rod 15 is linked to the lifting and lowering of the float 11. Specifically, the end of the shrinkage cavity 12 away from the interaction tube 9 is conical, and the tip of the cone is connected to the exhaust hole 13; the outer diameter of the ball plug 14 is smaller than the maximum inner diameter of the shrinkage cavity 12, and is larger than the inner diameter of the exhaust hole 13; a through hole 19 is provided at the junction of the interaction tube 9 and the exhaust head 10, and the pull rod 15 is provided A cross-rod is shaped and movable through the through hole 19, thereby maintaining the connection between the interaction tube 9 and the shrinking cavity 12, and does not affect the movement of the pull rod 15; the pull rod 15 is arranged along the axial direction of the shrinking cavity 12; the elastic member 16 is preferably a spring, and the setting of the elastic member 16 keeps pulling the pull rod 15, and the pull rod 15 drives the ball plug 14 to remain away from the exhaust hole 13, thereby connecting the interaction tube 9, the shrinking cavity 12 and the exhaust hole 13 in sequence; the linkage between the pull rod 15 and the floating block 11 is specifically as follows: when the floating block 11 descends, the pull rod 15 is pulled by the elastic member 16, driving the ball plug 14 away from the exhaust hole 13, and when the floating block 11 rises, the pull rod 15 is linked to move into the shrinking cavity 12, that is, driving the ball plug 14 against the inner wall of the shrinking cavity 12 to block the shrinking cavity 12 from connecting with the exhaust hole 13.

[0037] As a further preferred technical solution of this embodiment, a top rod 17 is fixedly provided on the upper end of the float 11. The top rod 17 is movably connected to the end of the pull rod 15 away from the ball plug 14 through a hinged connecting rod 18. Specifically, the upper and lower ends of the connecting rod 18 are hinged to the pull rod 15 and the top rod 17 respectively. In actual use of this technical solution, when the fluid flowing in the gradient tube 3 does not contain obvious gas, under the action of the fluid's own pressure, a part of the fluid enters the interaction tube 9 through the interaction port 6. The liquid level height in the interaction tube 9 is about half of the internal height of the interaction tube 9, thereby generating buoyancy to push the float 11. The float 11 maintains a certain height, and then pushes the connecting rod 18 through the top rod 17. The lower end of the connecting rod 18 approaches the upper end to tilt, and the upper end of the connecting rod 18 pushes the pull rod 15 to move into the shrinking cavity 12. The connecting rod 18 resists the elastic force of the elastic member 16 and drives the ball plug 14 to press against the inner wall of the shrinking cavity 12, blocking the shrinking cavity 1 2 is connected to the exhaust hole 13. At this time, the exhaust hole 13 does not exhaust. When the fluid flowing in the gradient tube 3 contains obvious gas, the gas will flow to the highest layer of the fluid and then enter the interactive tube 9 through the interactive port 6. Due to the entry of gas, the fluid level in the interactive tube 9 drops, the float 11 loses the support of the fluid and falls, and the elastic member 16 also releases its elastic potential energy to remain taut. As a result, the pull rod 15 is driven out of the contraction cavity 12, and the pull rod 15 drives the ball plug 14 away from the exhaust hole 13, so that the exhaust hole 13 is connected to the contraction cavity 12. That is, the exhaust hole 13 is opened and the gas in the interactive tube 9 can be discharged to the outside.

[0038] In another embodiment proposed by the present invention, a columnar electrode 20 is provided on the side direction of the inner wall of the flow tube 1, and the temperature difference block 4 is rotatably provided in the gradient tube 3. A reciprocating component for driving the temperature difference block 4 to rotate is provided on the gradient tube 3. The temperature difference block 4 guides the fluid flowing from the gradient tube 3 into the flow tube 1 in the upper and lower tangential directions of the columnar electrode 20 at both ends of the rotation range. Specifically, the columnar electrode 20 remains extended into the flow tube 1 to fully contact with the liquid, thereby completing electrical conduction to realize electromagnetic measurement. However, this also makes it easy for dirt in the fluid to accumulate on the columnar electrode 20, thereby reducing the measurement accuracy. The cylindrical electrode 20 is arranged horizontally and perpendicular to the axial direction of the flow tube 1; the upper end of the temperature difference block 4 is hinged on the inner top surface of the gradient tube 3, and the axial direction is parallel to the axial direction of the cylindrical electrode 20, and the lower end of the temperature difference block 4 can swing toward the inner side of the gradient tube 3; the setting of the reciprocating component allows the temperature difference block 4 to swing back and forth on the inner top surface of the gradient tube 3, and the swing range is preferably 10°-15°; the lower surface of the temperature difference block 4 guides the fluid in the gradient tube 3, and the two ends of the swing range of the temperature difference block 4 guide the fluid flowing from the gradient tube 3 into the flow tube 1 in the upper and lower directions of the cylindrical electrode 20 respectively. During the swinging process of the temperature difference block 4, the fluid it guides repeatedly impacts the side of the cylindrical electrode 20 facing the fluid entry direction, thereby avoiding the accumulation of dirt on the surface of the cylindrical electrode 20 by repeatedly changing the flow direction of the fluid.

[0039] The cam 23 is provided with a cam 23 for rotation in the movable chamber 21, and the cam 23 is linked to the movable chamber 21 through a one-way transmission assembly. The lower side of the cam 23 is provided with an up-and-down rod 24 for lifting and lowering, and the lower end of the up-and-down rod 24 is movably connected to the temperature difference block 4. Specifically, the movable chamber 21 is arranged on the upper side of the temperature control chamber 7; the rotating shaft of the oscillating member 22 is connected to the inner wall of the movable chamber 21 by a torsion spring. The setting of the torsion spring enables the oscillating member 22 to automatically maintain the position of vertically blocking the exhaust hole 13 without external force. When the exhaust hole 13 is exhausted, the oscillating member 22 can be pushed to swing. When the exhaust hole 13 stops exhausting, the oscillating member 22 elastically recovers; the swinging back and forth of the oscillating member 22 is transmitted to the position of only one direction of rotation by the one-way transmission assembly. The cam 23 is provided, thereby causing the cam 23 to rotate unidirectionally; the fluctuation rod 24 is preferably T-shaped, with the upper end corresponding to the lower side of the cam 23, and the lower end movably extending through the temperature control chamber 7 and provided with a sliding pin. The upper side of the temperature difference block 4 is provided with a sliding frame movably connected to the sliding pin, thereby ensuring that the rotation of the temperature difference block 4 and the lifting and lowering of the fluctuation rod 24 are linked and do not interfere with each other; in actual use, the gradient tube 3 is continuously circulated with fluid. Under the condition that the fluid continuously impacts the temperature difference block 4, the temperature difference block 4 is kept at the innermost side that does not swing out into the gradient tube 3, thereby keeping the upper end of the fluctuation rod 24 against the outer edge of the cam 23. Therefore, when the cam 23 rotates, the cam 23 can squeeze and push the fluctuation rod 24, so that the temperature difference block 4 can smoothly swing out into the gradient tube 3. As the cam 23 rotates cyclically, the temperature difference block 4 can swing back and forth, thereby guiding the fluid flowing from the gradient tube 3 into the flow tube 1 in the upper and lower directions of the cylindrical electrode 20 respectively.

[0040] As a further preferred technical solution of this embodiment, the one-way transmission assembly includes a rotary block 25 coaxially connected to the rotating shaft of the swing member 22, a pawl 26 elastically provided on the outer wall of the rotary block 25, and a ratchet 27 matching the pawl 26 is sleeved on the outer side of the rotary block 25. The ratchet 27 is rotatably set in the movable bin 21 and is connected to the cam 23 through a gear transmission. Specifically, the rotary block 25, the pawl 26 and the ratchet 27 constitute a one-way rotation transmission mechanism, so that the reciprocating swing of the swing member 22 is transmitted as a cyclic rotation of the cam 23.

[0041] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. An electromagnetic flowmeter, comprising a flow tube (1) and an instrument head (2) arranged on the flow tube (1), characterized in that: The inlet end of the flow tube (1) is set as a gradient tube (3), the inner top surface of the gradient tube (3) is sloped, and is set to continuously descend along the fluid guide height set in the flow tube (1), and further includes: A temperature difference block (4) is provided on the sloped inner top surface of the gradient tube (3), and a heating wire (5) is provided on the surface wall of the temperature difference block (4) facing the interior of the gradient tube (3); An exhaust assembly is provided at the upper end of the gradient tube (3), and an interactive port (6) is provided at the lower end thereof and corresponds to the highest position of the temperature difference block (4). The exhaust assembly is used to collect gas mixed in the flowing liquid in the flow tube (1) and discharge it to the outside; The exhaust assembly comprises an interactive tube (9) fixedly arranged at the upper end of the gradient tube (3), the interactive port (6) being arranged at the lower end of the interactive tube (9), an exhaust head (10) being arranged at the upper end of the side wall of the interactive tube (9); and an exhaust hole (13) being arranged at the end of the exhaust head (10); A columnar electrode (20) is provided on the side of the inner wall of the flow tube (1); the temperature difference block (4) is rotatably provided in the gradient tube (3); a reciprocating assembly for driving the temperature difference block (4) to rotate is provided on the gradient tube (3); the temperature difference block (4) guides the fluid flowing from the gradient tube (3) into the flow tube (1) in the upper and lower tangential directions of the columnar electrode (20) at both ends of the rotation range; The reciprocating assembly comprises a movable chamber (21) fixedly arranged on the gradient tube (3); a swinging member (22) is elastically rotatably arranged in the movable chamber (21); the upper end of the swinging member (22) extends out of the movable chamber (21) and reaches a position blocking the exhaust hole (13); a cam (23) is rotatably arranged in the movable chamber (21); the swinging member (22) is linked to the cam (23) through a one-way transmission assembly; a rising and falling rod (24) is movably arranged on the lower side of the cam (23); and the lower end of the rising and falling rod (24) is movably connected to the temperature difference block (4).

2. The electromagnetic flowmeter according to claim 1, characterized in that A temperature control chamber (7) is provided at the upper end of the gradient tube (3), a temperature control unit (8) is provided in the temperature control chamber (7), and the temperature control unit (8) is electrically connected to the heating wire (5).

3. The electromagnetic flowmeter according to claim 1, characterized in that A float (11) is movably provided in the interactive tube (9), and a switch assembly is provided in the exhaust head (10). The switch assembly is linked to the float (11). When the float (11) falls freely, the switch assembly controls the exhaust head (10) to open, and when the float (11) floats upward due to the buoyancy of the fluid, the switch assembly controls the exhaust head (10) to close.

4. The electromagnetic flowmeter according to claim 3, characterized in that The switch assembly includes a shrinkage cavity (12) provided in the exhaust head (10), the shrinkage cavity (12) is connected to the exhaust hole (13), a ball plug (14) is movably provided in the shrinkage cavity (12), an end of the ball plug (14) away from the exhaust hole (13) is fixedly connected to a pull rod (15), an end of the pull rod (15) away from the ball plug (14) is connected to the inner wall of the interaction tube (9) through an elastic member (16), and the movement of the pull rod (15) is linked to the lifting and lowering of the float (11).

5. The electromagnetic flowmeter according to claim 4, characterized in that: A push rod (17) is fixedly provided on the upper end of the floating block (11), and the push rod (17) is movably connected to the end of the pull rod (15) away from the ball plug (14) through a hinged connecting rod (18).

6. The electromagnetic flowmeter according to claim 4, characterized in that A through hole (19) is provided at the connection point between the interactive tube (9) and the exhaust head (10), and the pull rod (15) is provided in a cross-rod shape and movably passes through the through hole (19).

7. The electromagnetic flowmeter according to claim 1, characterized in that The one-way transmission assembly comprises a rotary block (25) coaxially connected to the rotating shaft of the swing member (22), a ratchet (26) elastically provided on the outer wall of the rotary block (25), a ratchet (27) matching the ratchet (26) provided on the outer side of the rotary block (25), and the ratchet (27) rotatably provided in the movable bin (21) and connected to the cam (23) via gear transmission.

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