Micro differential pressure transmitter

Abstract

The present application relates to a micro differential pressure transmitter, which includes a hollow shell, sleeves are arranged on the opposite inner side walls, and the axes of the opposite sleeves overlap, and there is a gap between the ends close to each other, and the spacing of the gap is adjustable; a balancing diaphragm is arranged at the gap; a balancing spring is partially arranged in the sleeve, and the part exposed from the sleeve is connected to the balancing diaphragm. The balancing spring is arranged in the sleeve, and the sleeve can support the balancing spring. When the balancing diaphragm is impacted by gas, the sleeve can reduce the swing range of the balancing diaphragm by limiting the range of movement of the balancing spring, and can reduce the swing of the balancing diaphragm, improve the measurement accuracy, and at the same time can reduce the damage of the balancing diaphragm due to excessive swing amplitude. The gap between the opposite sleeves can be adjusted, so that the sleeve can adjust the movement range of the balancing diaphragm, and then adjust the pressure measurement range.

Description

Technical Field

[0001] The present application relates to the field of transmitters, and in particular to a micro differential pressure transmitter. Background Art

[0002] Micro differential pressure transmitter is an important means of measuring liquid level. It is usually used to measure the liquid level of tank liquefied natural gas, liquid hydrogen and liquid oxygen. The current micro differential pressure transmitter has a balancing diaphragm and a balancing spring for stabilizing the balancing diaphragm. In order to achieve a better measurement effect, the balancing spring is in a natural state. In the actual measurement process, the balancing diaphragm is displaced due to the different air pressures on both sides. However, since the spring is completely in a natural state, this will cause the displacement of the balancing diaphragm not only to the left and right, but also to move up and down. This will easily cause the balancing diaphragm to be pulled, causing the balancing diaphragm to tilt under pressure, or swing randomly with the impact of gas, and even cause damage to the balancing diaphragm. In addition, the instability and shaking of the balancing diaphragm will lead to inaccurate measurement results. Summary of the invention

[0003] In order to improve detection accuracy and reduce damage to the balancing diaphragm, the present application provides a micro differential pressure transmitter.

[0004] A micro differential pressure transmitter provided in this application adopts the following technical solution:

[0005] A micro differential pressure transmitter, comprising:

[0006] The hollow shell has sleeves on its opposite inner side walls, and the axes of the opposite sleeves coincide with each other, and there is a gap between the ends close to each other, and the spacing of the gap is adjustable;

[0007] A balancing diaphragm is arranged at the gap;

[0008] A balancing spring is partially arranged in the sleeve, and a portion exposed from the sleeve is connected to the balancing diaphragm.

[0009] By adopting the above technical solution, the balancing diaphragm is connected to the inner wall of the shell through the balancing spring. The balancing diaphragm is not equally stressed on both sides and moves toward the side with lower air pressure. The displacement difference of the balancing diaphragm can be converted to obtain the liquid level of the detected liquid. The balancing spring is arranged in the sleeve, and the sleeve can support the balancing spring. When the balancing diaphragm is impacted by gas, the sleeve can reduce the swing range of the balancing diaphragm by limiting the range of motion of the balancing spring, and can reduce the swing of the balancing diaphragm, improve the measurement accuracy, and reduce the damage of the balancing diaphragm due to excessive swing amplitude. The gap between the relative sleeves can be adjusted, so that the sleeve can adjust the range of motion of the balancing diaphragm, and then adjust the pressure measurement range.

[0010] Optionally, a base is provided on the inner side walls opposite to the shell, the sleeve is threadedly connected to the base, and the spacing of the gap is changed by rotating the sleeve.

[0011] By adopting the above technical solution, the spacing of the gap between two opposite sleeves can be adjusted by adjusting the depth of the sleeve screwed into the base.

[0012] Optionally, on an inner side wall of the shell, connection points between the sleeve and the inner side wall are distributed on a circle.

[0013] By adopting the above technical solution, the balancing spring in the sleeve can stably support the balancing diaphragm.

[0014] Optionally, a rubber bellows is sleeved on the balancing diaphragm, and the rubber bellows is connected to the inner wall of the shell.

[0015] By adopting the above technical solution, the rubber bellows plays the role of connecting the balancing diaphragm and the housing, and its soft property makes it have less resistance to the balancing diaphragm, so that the balancing diaphragm can move freely in the housing.

[0016] Optionally, a gasket is provided in the sleeve, and the gasket is used to adjust the length of the balance spring extending out of the sleeve.

[0017] By adopting the above technical solution, the length of the balancing spring extending out of the sleeve can be adjusted by the number of gaskets, so that one end of multiple balancing springs connected to the balancing diaphragm can be in the same plane, and the balancing diaphragm is subjected to the same force from multiple balancing springs, which makes it convenient for the balancing spring to limit the balancing diaphragm to a preset position.

[0018] Optionally, the shell is provided with a through hole, a displacement connecting rod is passed through the through hole, one end of the displacement connecting rod is connected to the balance diaphragm, and the other end is connected to a display device.

[0019] By adopting the above technical solution, the displacement connecting rod can transmit the displacement of the balance diaphragm to the display device, so as to intuitively obtain the liquid level value of the detected liquid.

[0020] Optionally, a sealing device is provided at the connection between the displacement connecting rod and the housing.

[0021] By adopting the above technical solution, the sealing device can prevent the air pressure in the shell from leaking when relative displacement occurs between the displacement connecting rod and the output hole, thereby preventing the detection accuracy from being affected.

[0022] Optionally, a locking nut is sleeved on the sleeve, and the locking nut is tightened to abut against the base.

[0023] By adopting the above technical solution, the locking nut can increase the pre-tightening force between the sleeve and the base, and strengthen the connection between the sleeve and the base.

[0024] The present application discloses a micro differential pressure transmitter, in which a balancing diaphragm is connected to the inner wall of a housing through a balancing spring, and the balancing diaphragm is subjected to forces on both sides and does not move toward the side with lower air pressure at the same time, and the liquid level of the detected liquid can be converted by the displacement difference of the balancing diaphragm, and the balancing spring is arranged in a sleeve, and the sleeve can play a supporting role for the balancing spring. When the balancing diaphragm is impacted by gas, the sleeve can reduce the swing range of the balancing diaphragm by limiting the range of motion of the balancing spring, and can reduce the swing of the balancing diaphragm, improve the measurement accuracy, and at the same time can reduce the damage of the balancing diaphragm due to excessive swing amplitude. The gap between the relative sleeves can be adjusted, so that the sleeve can adjust the range of motion of the balancing diaphragm, and then adjust the pressure measurement range. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the system structure of an embodiment of the present application.

[0026] Figure 2 It is a cross-sectional view of the micro differential pressure transmitter according to an embodiment of the present application.

[0027] Figure 3 It is a schematic diagram of the gasket structure of an embodiment of the present application.

[0028] Explanation of the reference numerals: 1. tank body; 21. first pressure transmission pipeline; 211. first isolation valve; 22. second pressure transmission pipeline; 221. second isolation valve; 3. shell; 31. first pressure input connector; 32. second pressure input connector; 4. balancing diaphragm; 5. rubber bellows; 6. balancing spring; 7. sleeve; 8. base; 9. displacement connecting rod; 10. display device; 11. gasket; 12. rubber ring; 13. locking nut; 14. first chamber; 15. second chamber. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0030] Micro differential pressure transmitter is an important means of detecting liquid level. Micro differential pressure transmitter is usually used to measure the liquid level in closed tanks, such as tank liquefied natural gas, liquid hydrogen and liquid oxygen. Figure 1The tank body 1 contains the liquid whose level is to be detected. For example, natural gas is the liquefied natural gas in the tank, which is liquefied at low temperature. Since the ambient temperature is much higher than the temperature in the tank, the ambient temperature is continuously transmitted into the tank, causing the temperature in the tank to rise, and the liquefied natural gas is continuously gasified and condensed in the upper part of the tank body 1. Since the tank body 1 has the characteristics of sealing and heat preservation, if the gas in the upper part of the tank body 1 cannot be discharged to the outside, gas pressure acting on the surface of the liquid will be formed in the upper part of the tank body 1. In addition, during use, the continuous output and discharge of the gas in the tank body 1 will also cause fluctuations in the pressure in the tank. The above situations will affect the measurement of the liquid level in the tank.

[0031] When measuring the liquid level in the tank by the pressure measurement method, in order to overcome the above-mentioned influence, the differential pressure measurement method can be used, that is, the influence and error of the gas pressure in the upper part of the tank on the liquid level detection can be offset by the differential pressure measurement method.

[0032] The upper part of the tank body 1 is connected to a first pressure transmission pipeline 21, and a first isolation valve 211 is arranged at the connection between the first pressure transmission pipeline 21 and the tank body 1. The first pressure transmission pipeline 21 can transmit the isolated gas pressure to the micro differential pressure transmitter. The bottom of the tank body 1 is connected to a second pressure transmission pipeline 22, and a second isolation valve 221 is also arranged between the second pressure transmission pipeline 22 and the tank body 1. The second pressure transmission pipeline 22 can transmit the liquid pressure to the micro differential pressure transmitter.

[0033] The current micro differential pressure transmitter has a balancing diaphragm 4 and a balancing spring 6 for stabilizing the balancing diaphragm 4. In order to achieve a better measurement effect, the balancing spring 6 is in a natural state. During the actual measurement process, the balancing diaphragm 4 is displaced due to the different air pressures on both sides. However, since the spring is completely in a natural state, this will cause the displacement of the balancing diaphragm 4 not only to the left and right, but also to the up and down movement. This will easily cause the balancing diaphragm 4 to be pulled, causing the balancing diaphragm 4 to tilt under the action of pressure, or to swing randomly with the impact of the gas, and even cause the balancing diaphragm 4 to be damaged. In addition, the instability and shaking of the balancing diaphragm 4 will lead to inaccurate measurement results.

[0034] The present application discloses a micro differential pressure transmitter, referring to Figure 2 , including a hollow shell 3, a balancing diaphragm 4 and a balancing spring 6. Sleeves 7 are arranged on the opposite inner side walls of the shell 3, and the axes of the opposite sleeves 7 coincide with each other, and there is a gap between the ends close to each other, and the spacing of the gap is adjustable. The balancing diaphragm 4 is arranged in the gap, and the balancing spring 6 is partially arranged in the sleeve 7, and the part of the balancing spring 6 exposed from the sleeve 7 is connected to the balancing diaphragm 4.

[0035] The housing 3 may be a cylindrical hollow housing 3. Since the liquid to be detected is in a low temperature environment, the housing 3 may be made of a metal copper material with a high density to reduce the possibility of cracks and leakage in the low temperature environment of the housing 3. A rubber bellows 5 is sleeved on the balancing diaphragm 4. The rubber bellows 5 and the balancing diaphragm 4 may be an integrally formed circular sheet. The rubber bellows 5 is fixedly connected to the inner side wall of the cavity. The rubber bellows 5 is in a circular corrugated shape, and its soft characteristics make it less resistant to the balancing diaphragm 4, so that the balancing diaphragm 4 can move freely in the housing 3.

[0036] The barrier composed of the balancing diaphragm 4 and the rubber bellows 5 divides the chamber of the shell 3 into a first chamber 14 and a second chamber 15. A first pressure input connector 31 is provided in the first chamber 14, and the first pressure input connector 31 is used to connect with the first pressure transmission pipeline 21 of the tank body 1 to be detected, so that the gas pressure in the tank body 1 can be transmitted to the first chamber 14 through the first transmission pipeline; a second pressure input connector 32 is provided in the second chamber 15, and the second pressure input connector 32 is used to connect with the second pressure transmission pipeline 22, so that the liquid pressure in the tank body 1 can be transmitted to the second chamber 15 through the second transmission pipeline.

[0037] During the detection process, the first pressure input connector 31 is connected to the gas pressure in the tank body 1 to be detected, and the second pressure input connector 32 is connected to the liquid pressure in the tank body 1. Since the liquid pressure is equal to the sum of the gas pressure and the actual liquid pressure, and the liquid pressure is greater than the gas pressure, the two sides of the balancing diaphragm 4 are subjected to unbalanced air pressure and move to the side with low air pressure. The micro-differential pressure transmitter can obtain the liquid level of the detected liquid by converting the displacement of the balancing diaphragm 4. Since the balancing diaphragm 4 will shake under the impact of gas and affect the measurement result, the sleeve 7 can support the balancing spring 6. When the balancing diaphragm 4 is impacted by gas, the sleeve 7 can reduce the swing range of the balancing diaphragm 4 by limiting the active range of the balancing spring 6. When the balancing diaphragm 4 is impacted by gas, the swing of the balancing diaphragm 4 can be reduced, thereby improving the measurement accuracy and reducing the possibility of damage to the balancing diaphragm 4 due to excessive swinging amplitude. The gap between the relative sleeves 7 can be adjusted, so that the sleeve 7 can adjust the displacement range of the balancing diaphragm 4 while limiting the displacement of the balancing diaphragm 4, and the sleeve 7 can adapt to housings 3 and balancing springs 6 of different sizes, thereby improving the adaptability of the sleeve 7.

[0038] The gas pressure in the upper part of the tank is P1, and the liquid pressure exerted on the liquid surface by the gas pressure in the tank is P2. The actual liquid pressure is P, and P=P2-P1.

[0039] If the liquid level in the tank is H, and the conversion coefficient between pressure and liquid level is K, then H=KP, so that after knowing the pressure of the liquid in the tank, the liquid level in the tank can be calculated.

[0040] When the differential pressure measurement method is used to measure the liquid level in the tank, the gas pressure P1 in the tank is transmitted to the first chamber 14 through the first pressure input connector 31, and the liquid pressure P2 in the tank is transmitted to the second chamber 15 through the second pressure input connector 32. The gas pressure P1 acts on one side of the balancing diaphragm 4, and the liquid pressure P2 acts on the other side of the balancing diaphragm 4. Since the gas pressure P1 and the liquid pressure P2 act in opposite directions, the displacement of the balancing diaphragm 4 can output the effect of P=P2-P1, and the movement range of the balancing diaphragm 4 between the first chamber 14 and the second chamber 15 depends on the size of the gas pressure P1 and the liquid pressure P2.

[0041] In the embodiment of the present application, the inner wall of the shell 3 is provided with a base 8, and the base 8 can be a copper base. The sleeve 7 can be connected to the shell 3 through the base 8. The sleeve 7 is cylindrical, and one end connected to the base 8 has an external thread. The sleeve 7 can be screwed into the base 8 through the external thread, and the gap between the two relative sleeves 7 can be adjusted by adjusting the length of the sleeve 7 screwed into the base 8. The technician can adjust the gap between the two sleeves 7 according to the movement range of the balancing diaphragm 4. In this way, after the balancing spring 6 is installed, the height consistency of the six sleeves 7 can be further adjusted, and the pressure limit range can also be adjusted by adjusting the spacing of the gaps. When the balancing diaphragm 4 moves quickly or significantly in one direction, the sleeve 7 can support and limit the movement of the balancing diaphragm 4, avoiding the tearing of the rubber bellows 5 caused by the large movement of the balancing diaphragm 4.

[0042] After the sleeve 7 is screwed into the base 8, in order to further strengthen the connection between the sleeve 7 and the base 8, a locking nut 13 is also provided on the sleeve 7. The external thread on the sleeve 7 is exposed when the sleeve 7 is screwed into the base 8. The locking nut 13 is tightly connected to the above-mentioned exposed external thread. The locking nut 13 abuts against the surface of the base 8 to increase the pre-tightening force between the sleeve 7 and the base 8, making the connection between the sleeve 7 and the base 8 more secure.

[0043] The connection points between the base 8 located on the inner side wall of the same side of the shell 3 and the shell 3 are distributed on a circle, and the sleeve 7 connected to the base 8 and the balance spring 6 arranged in the sleeve 7 are all distributed on this circle. Specifically, three balance springs 6 can be arranged in each chamber, and the three balance springs 6 are evenly spaced and distributed on a circle, so that the balance springs 6 can play a stable supporting role for the balance diaphragm 4. The balance springs 6 in the first chamber 14 and the second chamber 15 are symmetrically arranged. Since the elastic coefficient of each balance spring 6 is the same and the installation position is symmetrical, the total elastic force of the two groups of balance springs 6 on both sides of the balance diaphragm 4 is the same, which can make the balance diaphragm 4 stable in the middle of the cavity and will not swing back and forth due to slight pressure interference. Of course, the number of balance springs 6 in the chamber can also be four or five. The number of balance springs 6 is not limited here. Specifically, a corresponding number of balance springs 6 can be set according to the size of the shell 3. When the size of the shell 3 increases, the number of balance springs 6 can be appropriately increased.

[0044] Reference Figure 3 Since the length of the balancing spring 6 cannot be completely consistent, in order to ensure that the force exerted on the balancing diaphragm 4 by each balancing spring 6 is consistent, a gasket 11 is arranged between the balancing spring 6 and the sleeve 7. The gasket 11 can adjust the length of the balancing spring 6 extending out of the sleeve 7, that is, by arranging different numbers of gaskets 11 between the spring and the base 8, the distance between the balancing spring 6 and the balancing diaphragm 4 in the free state can be adjusted, so that the free ends of the multiple horizontal springs are in the same plane, and the free ends of the balancing spring 6 can abut against the balancing diaphragm 4 in the free state.

[0045] In the embodiment of the present application, the balancing diaphragm 4 is connected to a displacement link 9, and an output hole for the displacement link 9 to pass through is provided on the housing 3. One end of the displacement link 9 is connected to the balancing diaphragm 4, and the other end passes through the output hole and is connected to a display device 10 disposed outside the housing 3. A connecting ring is provided between the displacement link 9 and the display device 10. The displacement link 9 can transmit the displacement of the balancing diaphragm 4 to the outside of the cavity, and transmit it to the display device 10 through the connecting ring. A sealing device is provided at the connection position of the displacement link 9 with the output hole. The sealing device can be a rubber ring 12. The rubber ring 12 is fixedly connected to the displacement link 9. The length of the rubber ring 12 is greater than the displacement length of the displacement link 9. When the displacement link 9 is displaced, the rubber ring 12 can always maintain close contact with the output hole to prevent the air pressure in the housing 3 from leaking.

[0046] The display device 10 can be a displacement display, in which a mechanical amplification device is provided. The mechanical amplification device can adjust the displacement-liquid level conversion coefficient and the amplification factor according to a preset ratio to keep the two consistent, so that the liquid level in the tank can be displayed through the displacement display after conversion.

[0047] The display device 10 may also be provided with an output device, which can convert the displacement of the displacement link 9 into an electrical signal and transmit the electrical signal remotely to an external device, so as to facilitate remote monitoring of the liquid level in the tank. The output device may be a non-contact magnetic displacement measuring device.

[0048] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A micro differential pressure transmitter, characterized in that: include: A hollow shell (3) is provided with sleeves (7) on opposite inner side walls thereof, the axes of the opposite sleeves (7) coincide with each other, and a gap is provided between the ends close to each other, and the spacing of the gap is adjustable; A base (8) is provided on the inner side wall opposite to the shell (3), the sleeve (7) is threadedly connected to the base (8), and the spacing of the gap is changed by rotating the sleeve (7); On an inner side wall of the housing (3), connection points between the sleeve (7) and the inner side wall are distributed on a circle; A balancing diaphragm (4) is arranged at the gap; The housing (3) is provided with a through hole, a displacement connecting rod (9) is inserted into the through hole, one end of the displacement connecting rod (9) is connected to the balance diaphragm (4), and the other end is connected to the display device (10); The balancing diaphragm (4) is sleeved with a rubber bellows (5), and the rubber bellows (5) is connected to the inner wall of the housing (3); A balancing spring (6) is partially disposed in the sleeve (7), and a portion exposed from the sleeve (7) is connected to the balancing diaphragm (4); A gasket (11) is arranged in the sleeve (7), and the gasket (11) is used to adjust the length of the balance spring (6) extending out of the sleeve (7).

2. The micro differential pressure transmitter according to claim 1, characterized in that: A sealing device is provided at the connection between the displacement connecting rod (9) and the housing (3).

3. The micro differential pressure transmitter according to claim 1, characterized in that: A locking nut (13) is sleeved on the sleeve (7), and the locking nut (13) is tightened to abut against the base (8).

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