Electromagnetic flowmeter

Abstract

The electromagnetic flowmeter comprises a flow tube and an instrument head, the inlet end of the flow tube is arranged to be a gradual change tube, the inner top face of the gradual change tube is in a slope shape, the electromagnetic flowmeter further comprises a temperature difference block, the temperature difference block is arranged on the slope-shaped inner top face of the gradual change tube, and a heating wire is arranged on the surface wall, facing the interior of the gradual change tube, of the temperature difference block; the exhaust assembly is arranged at the upper end of the gradual change pipe, an interaction opening is formed in the lower end of the exhaust assembly and corresponds to the highest position of the temperature difference block, and the exhaust assembly is used for collecting gas mixed in flowing liquid in the flow pipe and exhausting the gas to the outside. By arranging the gradual change pipe, fluid can be guided into the flow pipe with the small inner diameter from a pipeline with the large inner diameter, it is guaranteed that the straight pipe section at the position of the flow pipe is full of pipe through-flow, under the arrangement of the temperature difference block, bubbles are broken due to the internal and external pressure difference, generated gas enters the interaction opening and is exhausted to the outside through the exhaust assembly, and the effect that the fluid flows through the straight pipe section is achieved. It is guaranteed that through-flow fluid of the straight pipe section of the flow pipe does not contain bubbles, and the detection precision of the flowmeter is guaranteed.

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. It applies the principle of electromagnetic induction and measures the flow rate of the 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. The existing electromagnetic flowmeters can basically meet daily use 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, which are located on the same horizontal plane as the straight tube section and the bottom of the tube 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 arranged at the end of the straight tube section; the detection electrode includes a threaded rod and a head, and 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 arranged between the measuring tube and the detection electrode. The utility model makes the fluid in a full or nearly full state, and improves the accuracy of the measurement result; the detection electrode can be directly installed and disassembled without disassembling the entire measuring tube, which is convenient for cleaning, maintenance and replacement of the electrode, improves the maintainability of the equipment, and ensures the sealing.

[0004] As in the prior art of the above patent, the fluid in the straight pipe section cannot fill up the pipe or there are many bubbles 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 comprises 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 the fluid guide height set along the flow tube is arranged to continuously descend, and further comprises: a temperature difference block, which is arranged on the sloped inner top surface of the gradient tube, and a heating wire is arranged on the surface wall facing the inside of the gradient tube; an exhaust assembly, which is arranged at the upper end of the gradient tube, and an interactive port is arranged 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.

[0008] Preferably, a temperature control chamber is provided at the upper end of the tapered 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 interaction tube fixedly provided at the upper end of the tapered tube, the interaction port is provided at the lower end of the interaction tube, and an exhaust head is provided at the upper end of the side wall of the interaction tube.

[0010] Preferably, a floating block is movably provided in the interaction tube, a switch assembly is provided in the exhaust head, the switch assembly is linked with the floating block, when the floating block freely falls, the switch assembly controls the exhaust head to open, and when the floating block floats under the buoyancy of the fluid, the switch assembly controls the exhaust head to close.

[0011] Preferably, the switch assembly includes a reduced-diameter cavity provided in the exhaust head, an exhaust hole communicating with the reduced-diameter cavity is provided at the end of the exhaust head, a ball plug is movably provided in the reduced-diameter cavity, a pull rod is fixedly connected to one end of the ball plug away from the exhaust hole, and the other 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 with the lifting of the floating block.

[0012] Preferably, a top rod is fixedly provided at the upper end of the floating block, and the top 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 junction of the interaction tube and the exhaust head, and the pull rod is arranged in a cross-shaped rod shape and movably penetrates through the through hole.

[0014] Preferably, a columnar electrode is provided on the inner wall side of the flow tube, the thermoelectric module is rotatably provided in the tapered tube, a reciprocating assembly for driving the thermoelectric module to rotate is provided on the tapered tube, and at both ends of the rotation range of the thermoelectric module, the fluid flowing into the flow tube from the tapered tube is respectively guided to the upper cutting direction and the lower cutting direction of the columnar electrode.

[0015] Preferably, the reciprocating assembly includes a movable chamber fixedly provided on the tapered tube, a swinging member is elastically rotatably provided in the movable chamber, the upper end of the swinging member extends out of the movable chamber and reaches a position blocking the exhaust hole, a cam is rotatably provided in the movable chamber, the swinging member is linked with the cam through a one-way transmission assembly, a fluctuating rod is vertically movably provided under the cam, and the lower end of the fluctuating rod is movably connected to the thermoelectric module.

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

[0017] In the above technical solution, the beneficial effect of the present invention is:

[0018] By providing a tapered pipe, the electromagnetic flowmeter can introduce the fluid from a pipe with a larger inner diameter into a flow pipe with a smaller inner diameter, ensuring full-flow through the straight pipe section at the flow pipe. Moreover, with the arrangement of the temperature difference block, the bubbles existing in the upper layer of the fluid entering the tapered pipe can flow along the sloping inner top surface of the tapered pipe, thus coming into contact with the surface of the temperature difference block heated by the heating wire, causing the pressure difference inside and outside the bubbles to rupture. The generated gas then gathers towards the uppermost layer of the fluid, thus smoothly entering the interaction port and being discharged to the outside through the exhaust assembly, ensuring that the fluid flowing through the straight pipe section of the flow pipe is bubble-free and guaranteeing the detection accuracy of the flowmeter.

[0019] It should be understood that the foregoing general description and the following detailed description are merely exemplary and explanatory, rather than restrictive of the present disclosure.

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

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments recorded in the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings.

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

[0023] Figure 2 Front view sectional structure schematic diagram provided by the embodiment of the present invention;

[0024] Figure 3 Provided by the embodiment of the present invention Figure 2 Enlarged structure schematic diagram at A in;

[0025] Figure 4 Internal structure schematic diagram of the interaction pipe provided by the embodiment of the present invention;

[0026] Figure 5 Structure schematic diagram of the one-way transmission assembly provided by the embodiment of the present invention.

[0027] Description of the reference numerals:

[0028] 1. Flow tube; 2. Meter head; 3. Gradual change tube; 4. Temperature difference block; 5. Heating wire; 6. Interaction port; 7. Temperature control chamber; 8. Temperature control unit; 9. Interaction tube; 10. Exhaust head; 11. Floating block; 12. Reduced orifice cavity; 13. Exhaust hole; 14. Ball plug; 15. Pull rod; 16. Elastic member; 17. Thrust rod; 18. Connecting rod; 19. Through hole; 20. Columnar electrode; 21. Movable chamber; 22. Swing member; 23. Cam; 24. Undulating rod; 25. Rotating block; 26. Pawl; 27. Ratchet wheel. Detailed implementation manners

[0029] To make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0030] Please refer to Figures 1-5 , an electromagnetic flowmeter provided by an embodiment of the present invention includes a flow tube 1 and a meter head 2 provided on the flow tube 1. The inlet end of the flow tube 1 is provided as a gradual change tube 3. The inner top surface of the gradual change tube 3 is in a slope shape and continuously decreases along the set fluid guiding height of the flow tube 1. It further includes: a temperature difference block 4, which is arranged on the sloped inner top surface of the gradual change tube 3, and a heating wire 5 is arranged on the surface of the wall facing the inside of the gradual change tube 3; an exhaust assembly, which is arranged at the upper end of the gradual change tube 3, and an interaction port 6 is arranged at its lower end and corresponds to the highest position of the temperature difference block 4. It is used to collect the 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 meter head 2 integrates functions such as signal processing, calculation, display, communication, and power management, and is responsible for converting the sensor signal into readable flow data and implementing system control. A connecting plate is provided at the end of the tapered tube 3 for connecting to the monitoring pipeline, and a connection port matching the end of the tapered tube 3 is provided on the monitoring pipeline; the maximum cross-sectional flux of the tapered tube 3 is greater than the cross-sectional flux of the flow tube 1, and from the end to the end connected to the flow tube 1, the cross-sectional flux of the tapered tube 3 gradually decreases smoothly until it is the same as the cross-sectional flux of the flow tube 1. The temperature difference block 4 is arranged along the sloping inner top surface of the tapered tube 3; the temperature difference block 4 is made of heat-conducting material, or at least the surface of the temperature difference block 4 facing the inside of the tapered tube 3 is heat-conducting; the heating wire 5 is used to raise the temperature of the surface of the temperature difference block 4 facing the inside of the tapered tube 3, and the temperature is higher than the temperature of the fluid flowing through the tapered tube 3. When the bubbles floating in the upper layer of the fluid come into contact with the surface of the temperature difference block 4, the internal and external temperature differences of the bubbles are generated and they are likely to burst. The exhaust assembly is a passive structure. When the fluid entering the tapered tube 3 contains obvious gas, the gas can be introduced through the interaction port 6 and discharged to the outside. When the fluid entering the tapered tube 3 does not contain obvious gas, a part of the fluid is introduced through the interaction port 6, but the fluid is not discharged to the outside. In the actual use of this technical solution, through the setting of the tapered tube 3, the fluid can be introduced from a pipeline with a larger inner diameter into the flow tube 1 with a smaller inner diameter, ensuring full-tube flow in the straight tube section at the flow tube 1. Moreover, with the setting of the temperature difference block 4, the bubbles existing in the upper layer of the fluid entering the tapered tube 3 can flow along the sloping inner top surface of the tapered tube 3, so as to come into contact with the surface of the temperature difference block 4 heated by the heating wire 5, causing the internal and external pressure differences of the bubbles to burst. The generated gas then gathers towards the uppermost layer of the fluid, and thus smoothly enters the interaction port 6 and is discharged to the outside through the exhaust assembly, ensuring that the fluid flowing through the straight tube section of the flow tube 1 does not contain bubbles and ensuring the detection accuracy of the flowmeter.

[0032] Compared with the prior art, an electromagnetic flowmeter proposed in an embodiment of the present invention can introduce the fluid from a pipeline with a larger inner diameter into the flow tube 1 with a smaller inner diameter through the setting of the tapered tube 3, ensuring full-tube flow in the straight tube section at the flow tube 1. Moreover, with the setting of the temperature difference block 4, the bubbles existing in the upper layer of the fluid entering the tapered tube 3 can flow along the sloping inner top surface of the tapered tube 3, so as to come into contact with the surface of the temperature difference block 4 heated by the heating wire 5, causing the internal and external pressure differences of the bubbles to burst. The generated gas then gathers towards the uppermost layer of the fluid, and thus smoothly enters the interaction port 6 and is discharged to the outside through the exhaust assembly, ensuring that the fluid flowing through the straight tube section of the flow tube 1 does not contain bubbles and ensuring the detection accuracy of the flowmeter.

[0033] As a preferred technical solution of this embodiment, a temperature control chamber 7 is provided at the upper end of the tapered tube 3. A temperature control unit 8 is arranged 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 arranged in the temperature control chamber 7. The power supply is preferably externally powered and is used to supply power to the heating wire 5, which is prior art and will not be elaborated.

[0034] As a preferred technical solution of this embodiment, the exhaust assembly includes an interaction tube 9 fixedly arranged at the upper end of the tapered tube 3. The interaction port 6 is arranged at the lower end of the interaction tube 9. An exhaust head 10 is arranged at the upper end of the side wall of the interaction tube 9. Specifically, the inside of the interaction tube 9 communicates with the inside of the tapered tube 3 through the interaction port 6. Under its own pressure, a part of the fluid in the tapered tube 3 can enter the interaction tube 9 through the interaction port 6. When there is gas in the fluid, the gas can also enter the interaction tube 9 through the interaction port 6 by buoyancy, thereby reducing the height of the fluid level in the interaction tube 9; the exhaust head 10 corresponds to the upper end of the interaction tube 9 and is connected.

[0035] As a further preferred technical solution of this embodiment, a floating block 11 is movably arranged in the interaction tube 9. A switch assembly is arranged in the exhaust head 10. The switch assembly is linked with the floating block 11. When the floating block 11 falls freely, the switch assembly controls the exhaust head 10 to open. When the floating block 11 floats under the buoyancy of the fluid, the switch assembly controls the exhaust head 10 to close. Specifically, the outer diameter of the floating block 11 is smaller than the inner diameter of the interaction tube 9, that is, there is a gap between the side surface of the floating block 11 and the inner wall of the interaction tube 9 to facilitate the passage of gas; the linkage between the switch assembly and the floating block 11 enables the switch assembly to passively control the opening and closing of the exhaust head 10; when the floating block 11 floats in the interaction tube 9, that is, the height of the fluid level in the interaction tube 9 is relatively high and less gas or no additional gas enters the interaction tube 9. At this time, the corresponding switch assembly controls the exhaust head 10 to close; when the floating block 11 falls in the interaction tube 9, that is, the height of the fluid level in the interaction tube 9 is relatively low and more gas enters the interaction tube 9. At this time, the corresponding switch assembly controls the exhaust head 10 to open to discharge the 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, an exhaust hole 13 connected to the shrinkage cavity 12 is arranged at the end of the exhaust head 10, a ball plug 14 is movably arranged in the shrinkage cavity 12, and a pull rod 15 is fixedly connected to the end of the ball plug 14 away from the exhaust hole 13, 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, and 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 arranged at the junction of the interaction tube 9 and the exhaust head 10, and the pull rod 15 is arranged A cross-rod-shaped and movable through-hole 19 is provided, thereby maintaining the communication 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 provided 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 to press against the inner wall of the shrinking cavity 12 to block the connection between the shrinking cavity 12 and the exhaust hole 13.

[0037] As a further preferred technical solution of this embodiment, a top rod 17 is fixedly arranged at the upper end of the floating block 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 respectively hinged to the pull rod 15 and the top rod 17. 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 self-pressure of the fluid, a part of the fluid enters the interaction tube 9 through the interaction port 6, and the liquid level height in the interaction tube 9 is near half of the internal height of the interaction tube 9, thereby generating a buoyancy force to push the floating block 11. The floating block 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 incline, and the upper end of the connecting rod 18 then pushes the pull rod 15 to move into the contraction cavity 12. The connecting rod 18 resists the elastic force of the elastic member 16 and drives the ball plug 14 to abut against the inner wall of the contraction cavity 12, blocking the communication between the contraction cavity 12 and the exhaust hole 13. At this time, the exhaust hole 13 does not exhaust gas; 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 interaction tube 9 through the interaction port 6. Due to the entry of the gas, the liquid level height of the fluid in the interaction tube 9 decreases, and the floating block 11 loses the support of the fluid and falls. Moreover, the elastic member 16 also releases elastic potential energy to maintain tension. Therefore, 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 communicated with the contraction cavity 12, that is, the exhaust hole 13 is opened to discharge the gas in the interaction tube 9 to the outside.

[0038] In another embodiment proposed by the present invention, a columnar electrode 20 is provided on the inner wall side of the flow tube 1. The temperature difference block 4 is rotatably arranged in the tapered tube 3. A reciprocating assembly for driving the temperature difference block 4 to rotate is arranged on the tapered tube 3. At both ends of the rotation range of the temperature difference block 4, the fluid flowing into the flow tube 1 from the tapered tube 3 is respectively guided to the upper cutting direction and the lower cutting direction of the columnar electrode 20. Specifically, the columnar electrode 20 remains inserted into the flow tube 1 to fully contact the liquid, thereby completing electrical conduction to achieve electromagnetic measurement. However, due to this, dirt existing in the fluid is likely to accumulate on the columnar electrode 20, thereby reducing the measurement accuracy. The columnar electrode 20 is horizontally and perpendicularly arranged along 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 tapered tube 3, and the axial direction is parallel to the axial direction of the columnar electrode 20. The lower end of the temperature difference block 4 can swing towards the inner side of the tapered tube 3; the arrangement of the reciprocating assembly enables the temperature difference block 4 to reciprocally swing on the inner top surface of the tapered tube 3, and the swing range is preferably 10° - 15°; the lower surface of the temperature difference block 4 guides the fluid in the tapered tube 3. At both ends of the swing range of the temperature difference block 4, the fluid flowing into the flow tube 1 from the tapered tube 3 is respectively guided to the upper cutting direction and the lower cutting direction of the columnar electrode 20. During the swinging process of the temperature difference block 4, the guided fluid repeatedly impacts on one side of the columnar electrode 20 facing the fluid inlet direction. Thus, by the fluid with repeatedly changing flow directions, dirt accumulation on the surface area of the columnar electrode 20 is avoided.

[0039] As a preferred technical solution of this embodiment, the reciprocating assembly includes a movable bin 21 fixedly arranged on the tapered tube 3. An oscillating member 22 is elastically rotatably arranged in the movable bin 21. The upper end of the oscillating member 22 extends out of the movable bin 21 and reaches the position blocking the exhaust hole 13. A cam 23 is rotatably arranged in the movable bin 21. The oscillating member 22 is linked with the cam 23 through a one-way transmission assembly. A fluctuating rod 24 is arranged in a lifting and lowering manner on the lower side of the cam 23. The lower end of the fluctuating rod 24 is movably connected with the temperature difference block 4. Specifically, the movable bin 21 is arranged above the temperature control bin 7; the rotating shaft of the oscillating member 22 is connected with the inner wall of the movable bin 21 through 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 exhausts, the oscillating member 22 can be pushed to swing. When the exhaust hole 13 stops exhausting, the oscillating member 22 elastically recovers; the reciprocating swing of the oscillating member 22 only transmits the rotation in one single direction to the cam 23 through the one-way transmission assembly, thereby enabling the cam 23 to rotate in a one-way cycle; the fluctuating rod 24 is preferably T-shaped, with the upper end corresponding to the lower side of the cam 23, and the lower end movably penetrates and extends into the temperature control bin 7 and is provided with a sliding pin. A sliding frame movably connected with the sliding pin is arranged on the upper side of the temperature difference block 4, thereby ensuring that the rotation of the temperature difference block 4 is linked with the lifting of the fluctuating rod 24 without interference; in actual use of the tapered tube 3, a continuously flowing fluid passes through it. Under the condition that the fluid continuously impacts the temperature difference block 4, the temperature difference block 4 is kept at the innermost side where it does not swing out into the tapered tube 3. Thus, the upper end of the fluctuating rod 24 is kept in contact with the outer edge of the cam 23. Then, when the cam 23 rotates, the cam 23 can squeeze and push the fluctuating rod 24, so that the temperature difference block 4 can swing out into the tapered tube 3 smoothly. With the cyclic rotation of the cam 23, the temperature difference block 4 can perform a reciprocating swing, realizing guiding the fluid flowing into the flow tube 1 from the tapered tube 3 to the upper cutting direction and the lower cutting direction of the columnar electrode 20 respectively.

[0040] As a further preferred technical solution of this embodiment, the one-way transmission assembly includes a rotating block 25 coaxially connected with the rotating shaft of the oscillating member 22. A pawl 26 is elastically arranged on the outer wall of the rotating block 25. A ratchet wheel 27 matching the pawl 26 is sleeved outside the rotating block 25. The ratchet wheel 27 is rotatably arranged in the movable bin 21 and is connected with the cam 23 through a gear transmission. Specifically, the rotating block 25, the pawl 26 and the ratchet wheel 27 constitute a mechanism for one-way transmission of rotation, enabling the reciprocating swing of the oscillating member 22 to be transmitted into the cyclic rotation of the cam 23.

[0041] Only some exemplary embodiments of the present invention have been described by way of illustration above. Without doubt, for those of ordinary skill in the art, the described embodiments can be modified in various different 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 protection scope of the claims of the present invention.

Claims

1. An electromagnetic flowmeter, comprising a flow tube (1) and a meter head (2) provided on the flow tube (1), characterized in that, The inlet end of the flow tube (1) is provided as a tapered tube (3). The inner top surface of the tapered tube (3) is sloped and continuously decreases along the fluid guiding height set for the flow tube (1). It further includes: A temperature difference block (4) which is arranged on the sloped inner top surface of the tapered tube (3), and a heating wire (5) is arranged on the surface wall facing the inside of the tapered tube (3); An exhaust assembly which is arranged at the upper end of the tapered tube (3). Its lower end is provided with an interaction port (6) corresponding to the highest position of the temperature difference block (4), and it is used to collect the gas mixed in the flowing liquid in the flow tube (1) and discharge it to the outside.

2. The electromagnetic flowmeter according to claim 1, wherein A temperature control bin (7) is arranged at the upper end of the tapered tube (3). A temperature control unit (8) is arranged in the temperature control bin (7), and the temperature control unit (8) is electrically connected to the heating wire (5).

3. The electromagnetic flowmeter according to claim 1, wherein, The exhaust assembly includes an interaction tube (9) fixedly arranged at the upper end of the tapered tube (3). The interaction port (6) is arranged at the lower end of the interaction tube (9), and an exhaust head (10) is arranged at the upper end of the side wall of the interaction tube (9).

4. The electromagnetic flowmeter according to claim 3, wherein, A floating block (11) is movably arranged in the interaction tube (9). A switch assembly is arranged in the exhaust head (10). The switch assembly is linked with the floating block (11). When the floating block (11) freely falls, the switch assembly controls the exhaust head (10) to open, and when the floating block (11) floats under the buoyancy of the fluid, the switch assembly controls the exhaust head (10) to close.

5. The electromagnetic flowmeter according to claim 4, wherein, The switch assembly includes a reduced-diameter cavity (12) arranged in the exhaust head (10). An exhaust hole (13) communicating with the reduced-diameter cavity (12) is arranged at the end of the exhaust head (10). A ball plug (14) is movably arranged in the reduced-diameter cavity (12). One end of the ball plug (14) far from the exhaust hole (13) is fixedly connected with a pull rod (15). The other end of the pull rod (15) far 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 with the lifting of the floating block (11).

6. The electromagnetic flowmeter according to claim 5, characterized in that, A top rod (17) is fixedly arranged at the upper end of the floating block (11). The top rod (17) is movably connected to the end of the pull rod (15) far from the ball plug (14) through a hinged connecting rod (18).

7. The electromagnetic flowmeter according to claim 5, characterized in that, A through hole (19) is arranged at the junction of the interaction tube (9) and the exhaust head (10). The pull rod (15) is arranged in a cross-shaped rod shape and movably passes through the through hole (19).

8. The electromagnetic flowmeter according to claim 5, characterized in that, A columnar electrode (20) is arranged on the inner wall side of the flow tube (1). The temperature difference block (4) is rotatably arranged in the tapered tube (3). A reciprocating assembly for driving the temperature difference block (4) to rotate is arranged on the tapered tube (3). At both ends of the rotation range of the temperature difference block (4), the tapered tube (3) guides the fluid flowing into the flow tube (1) to the upper cutting direction and the lower cutting direction of the columnar electrode (20) respectively.

9. The electromagnetic flowmeter according to claim 8, characterized in that, The reciprocating assembly includes a movable chamber (21) fixedly arranged on a tapered tube (3). A swing member (22) is elastically and rotatably arranged in the movable chamber (21). The upper end of the swing member (22) extends out of the movable chamber (21) and reaches a position for blocking the exhaust hole (13). A cam (23) is rotatably arranged in the movable chamber (21). The swing member (22) is linked and connected with the cam (23) through a one-way transmission assembly. A undulating rod (24) is arranged in a lifting and lowering manner on the lower side of the cam (23). The lower end of the undulating rod (24) is movably connected with a temperature difference block (4).

10. The electromagnetic flowmeter according to claim 9, characterized in that, The one-way transmission assembly includes a rotating block (25) coaxially connected with the rotating shaft of the swing member (22). A pawl (26) is elastically arranged on the outer wall of the rotating block (25). A ratchet wheel (27) matching the pawl (26) is sleeved outside the rotating block (25). The ratchet wheel (27) is rotatably arranged in the movable chamber (21) and is connected with the cam (23) through a gear transmission.

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