Support device for balancing spring in differential pressure transmitter and differential pressure transmitter

Abstract

The present application relates to a supporting device for a balancing spring in a differential pressure transmitter and a differential pressure transmitter, which comprises an inner sleeve and a balancing spring arranged in the inner sleeve, wherein the balancing spring extends from the inner sleeve, and the extending portion is used to be connected to a balancing diaphragm, and the balancing spring contacts the inner surface of the inner sleeve, and the inner sleeve is made of polyetheretherketone, and the balancing spring supports the balancing diaphragm. The inner sleeve supports the balancing diaphragm, and the inner sleeve is made of polyetheretherketone, which has a self-lubricating property. When the balancing spring contacts the inner sleeve, there is no need to apply grease to the inner sleeve, so as to reduce the friction between the balancing spring and the inner sleeve.

Description

Technical Field

[0001] The present application relates to the technical field of transmitters, and in particular to a supporting device for a balancing spring in a differential pressure transmitter and a 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 balance diaphragm and a balance spring for stabilizing the balance diaphragm. A sleeve is provided on the balance spring, and the sleeve supports the spring. In order to reduce the friction coefficient between the balance spring and the sleeve, grease is applied on the inner surface of the sleeve and the balance spring. However, in a low temperature environment, the grease is prone to solidification and hardening. In addition, the gas to be detected usually contains moisture. Water vapor will also condense on the inner wall of the sleeve and the surface of the spring in a low temperature environment. Both will increase the resistance of the spring during movement, affect the linear movement of the spring, and cause errors in the measurement results. Summary of the invention

[0003] In order to improve the lubrication between a supporting device and a balancing spring in a differential pressure transmitter, the present application provides a supporting device for a balancing spring in a differential pressure transmitter and a differential pressure transmitter.

[0004] In a first aspect, the present application provides a supporting device for a balancing spring in a differential pressure transmitter, which adopts the following technical solution:

[0005] A supporting device for a balancing spring in a differential pressure transmitter comprises: an inner sleeve and a balancing spring arranged in the inner sleeve, wherein the balancing spring extends from the inner sleeve, and the extended portion is used to be connected to a balancing diaphragm, and the balancing spring contacts the inner surface of the inner sleeve, and the inner sleeve is made of polyetheretherketone.

[0006] By adopting the above technical scheme, the balance spring is arranged in the inner sleeve, and the part of the balance spring extending from the inner sleeve is connected to the balance diaphragm. The balance spring supports the balance diaphragm, and the inner sleeve supports the balance diaphragm. The inner sleeve is made of polyetheretherketone, which has a self-lubricating property. When the balance spring contacts the inner sleeve, there is no need to apply grease to the inner sleeve, so as to reduce the friction between the balance spring and the inner sleeve.

[0007] Optionally, an inner side wall of the inner sleeve is provided with an embedding groove, and graphite powder is embedded in the embedding groove.

[0008] By adopting the above technical solution, when the graphite powder in the embedded groove falls off normally or there is moisture, the friction between the balance spring and the inner sleeve bracket can be further reduced, and the friction resistance of the inner sleeve to the balance spring can be reduced.

[0009] Optionally, it also includes an outer sleeve sleeved on the inner sleeve, and the outer sleeve is made of copper.

[0010] By adopting the above technical solution, the copper outer sleeve can protect the inner sleeve, the copper outer layer has the characteristic of low temperature resistance, and the copper sleeve is easy to process.

[0011] In a second aspect, the present application also provides a differential pressure transmitter, comprising:

[0012] At least two supporting devices according to any one of claims 1 to 3;

[0013] A hollow shell, with at least one supporting device disposed on each of the opposite inner side walls, and the axes of the opposite supporting devices coincide with each other, and there is a gap between the ends close to each other, and the spacing of the gap is adjustable;

[0014] A balancing diaphragm is arranged at the gap;

[0015] The portion of the balance spring in the supporting device extending out of the inner sleeve is connected to the balance diaphragm.

[0016] 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.

[0017] Optionally, a base is provided between the outer sleeve and the inner wall.

[0018] Optionally, the base is provided with a groove, the side wall of the groove has a thread, the outer sleeve is threadedly connected to the base, and the outer sleeve can be rotated to adjust the distance between two opposing supporting devices.

[0019] 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.

[0020] Optionally, on an inner side wall of the shell, connection points between the supporting device and the inner side wall are distributed on a circle.

[0021] By adopting the above technical solution, the balancing spring in the sleeve can stably support the balancing diaphragm.

[0022] Optionally, a gasket is provided in the inner sleeve, and the gasket is used to adjust the length of the balance spring extending out of the inner sleeve.

[0023] 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.

[0024] The present application discloses a supporting device for a balancing spring in a differential pressure transmitter, wherein the balancing spring is arranged in an inner sleeve, and the portion of the balancing spring extending from the inner sleeve is connected to a balancing diaphragm, the balancing spring supports the balancing diaphragm, the inner sleeve supports the balancing diaphragm, and the inner sleeve is made of polyetheretherketone, which has a self-lubricating property. When the balancing spring contacts the inner sleeve, there is no need to apply grease to the inner sleeve, so as to reduce the friction between the balancing spring and the inner sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the differential pressure transmitter according to an embodiment of the present application.

[0026] Figure 2 It is a schematic diagram of the structure of a supporting device for a balancing spring in a differential pressure transmitter according to an embodiment of the present application.

[0027] Figure 3 yes Figure 2 A is an enlarged view of the middle image.

[0028] Figure 4 It is a schematic diagram of the working environment of the differential pressure transmitter according to an embodiment of the present application.

[0029] Explanation of the reference numerals: 01, shell; 011, first chamber; 012, second chamber; 02, balancing diaphragm; 03, balancing spring; 04, supporting device; 041, outer sleeve; 042, inner sleeve; 0421, embedding groove; 05, rubber bellows; 06, base; 07, locking nut; 08, tank body; 091, first pressure transmission pipeline; 0911, first isolating valve; 092, second pressure transmission pipeline; 0921, second isolating valve; 10, gasket; 11, displacement connecting rod; 12, sealing device; 13, display device. DETAILED DESCRIPTION

[0030] 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.

[0031] In the differential pressure transmitter, the balance spring 03 is a component that directly affects the measurement accuracy. In order to increase the stability of the balance spring 03, a directional support device 04 is usually set on the outer sleeve of the balance spring 03 to support and position the balance spring 03. The slight bending of the balance spring 03 will increase the friction resistance between it and the pipe wall, causing measurement errors. In order to reduce the friction between the balance spring 03 and the support device 04, grease is usually applied to the inner wall of the support device 04 and the outer surface of the balance spring 03. However, in actual use, the temperature of the gas being detected is usually low, the external environment temperature is higher than the temperature of the gas being measured, and the gas being measured inevitably carries moisture. There is a temperature difference between the inside and outside of the shell 01, which makes the inner wall of the support device 04 and the surface of the spring very easy to condense, and the grease will also solidify and harden, increasing the resistance of the balance spring 03 to the movement in the support device 04, affecting the normal linear movement of the balance spring 03, and causing measurement errors.

[0032] A differential pressure transmitter disclosed in the present application, referring to Figure 1 , including a hollow shell 01, a balancing diaphragm 02 and a balancing spring 03. Support devices 04 are arranged on the opposite inner walls of the shell 01, and the axes of the opposite supporting devices 04 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 02 is arranged in the gap, and the balancing spring 03 is partially arranged in the supporting device 04, and the part of the balancing spring 03 exposed from the supporting device 04 is connected to the balancing diaphragm 02.

[0033] The housing 01 may be a cylindrical hollow housing 01. Since the liquid to be detected is in a low temperature environment, the housing 01 may be made of a high-density copper material to reduce the possibility of cracks and leakage in the low temperature environment of the housing 01. A rubber bellows 05 is sleeved on the balancing diaphragm 02. The rubber bellows 05 and the balancing diaphragm 02 may be an integrally formed circular sheet. The rubber bellows 05 is fixedly connected to the inner wall of the cavity. The rubber bellows 05 is in a circular corrugated shape, and its soft characteristics make it less resistant to the balancing diaphragm 02, so that the balancing diaphragm 02 can move freely in the housing 01.

[0034] Reference Figure 2The inner wall of the housing 01 is provided with a base 06, and the support device 04 can be connected to the housing 01 through the base 06. Specifically, the base 06 is provided with a groove, and the side wall of the groove has a thread. The support device 04 includes an outer sleeve 041 and an inner sleeve 042. The outer sleeve 041 and the inner sleeve 042 are interference fit. The outer sleeve 041 and the inner sleeve 042 are both cylinders. One end of the outer sleeve 041 has an outer thread. The outer layer can be screwed into the base 06, and can be rotated to adjust the distance between the two relative support devices 04. The technician can adjust the gap between the two support devices 04 according to the range of motion of the balance diaphragm 02. In this way, after the balance spring 03 is installed, when multiple support devices 04 are provided on each side, the height consistency of the multiple support devices 04 can be further adjusted, and the pressure limit range can also be adjusted by adjusting the spacing of the gaps. When the balancing diaphragm 02 moves rapidly or significantly in one direction, the support device 04 can support and limit the movement of the balancing diaphragm 02, thereby preventing the rubber bellows 05 from being torn due to the significant movement of the balancing diaphragm 02. The balancing spring 03 is disposed in the inner sleeve 042, and the support device 04 supports and limits the balancing spring 03.

[0035] The connection points between the base 06 located on the inner side wall of the same side of the shell 01 and the shell 01 are distributed on a circle, and the support device 04 connected to the base 06 and the balance spring 03 arranged in the support device 04 are all distributed on this circle. Specifically, three balance springs 03 can be arranged in each chamber, and the three balance springs 03 are evenly spaced and distributed on a circle, so that the balance spring 03 can play a stable supporting role for the balance diaphragm 02. The balance springs 03 in the first chamber 011 and the second chamber 012 are symmetrically arranged. Since the elastic coefficient of each balance spring 03 is the same and the installation position is symmetrical, the total elastic force of the two groups of balance springs 03 on both sides of the balance diaphragm 02 is the same, which can make the balance diaphragm 02 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 03 in the chamber can also be four or five. The number of balance springs 03 is not limited here. Specifically, a corresponding number of balance springs 03 can be set according to the size of the shell 01. When the size of the shell 01 increases, the number of balance springs 03 can be appropriately increased.

[0036] Reference Figure 3Since the length of the balancing spring 03 cannot be completely consistent, but in order to ensure that the force exerted on the balancing diaphragm 02 by each balancing spring 03 is consistent, a gasket 10 is arranged between the balancing spring 03 and the supporting device 04. The gasket 10 can adjust the length of the balancing spring 03 extending out of the supporting device 04, that is, by arranging different numbers of gaskets 10 between the spring and the base 06, the distance between the balancing spring 03 and the balancing diaphragm 02 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 springs 03 can abut against the balancing diaphragm 02 in the free state.

[0037] The outer sleeve 041 is made of copper with a high density. The copper material has the characteristic of being resistant to low temperatures. It is not easy to crack when working in a low temperature environment. In addition, the copper outer sleeve 041 can be mounted on the inner sleeve 042 after heating. The copper outer sleeve 041 after cooling can be firmly connected to the inner sleeve 042. When working in a low temperature environment, the connection between the outer sleeve 041 and the inner sleeve 042 will be tighter. Copper with a high density can be processed into threads with high precision, so that when adjusting the spacing of the relative support devices 04, the adjustment precision is high, which can reach 100 micron level.

[0038] The inner sleeve 042 is made of polyetheretherketone, which can be a new type of modified polyetheretherketone semi-crystalline engineering plastic with a lubricant added. This material has extremely excellent physical and mechanical properties and can replace traditional materials such as metals and ceramics in many special occasions. In particular, it has self-lubricating properties. When the inner wall of the inner sleeve 042 condenses, the properties of the polyetheretherketone material can increase the lubricity between the inner sleeve 042 and the balance spring 03, and reduce the resistance of the balance spring 03 during movement. Moreover, this material has excellent performance in terms of resistance to sliding wear and micro-motion wear loss. It can still maintain high wear resistance and low friction coefficient at an ambient temperature of -200°C to 250°C, and can withstand the friction of the balance spring 03. In addition, this material has high rigidity, stable dimensions, and a small linear expansion coefficient. It is suitable for connection with the copper outer sleeve 041 and can work for a long time in harsh environments.

[0039] In the embodiment of the present application, the inner wall of the inner sleeve 042 is provided with an embedding groove 0421, and graphite powder is embedded in the embedding groove 0421. The embedding groove 0421 can be a ring-shaped embedding groove 0421. The graphite powder is micro-graphite powder with a mesh size lower than 200. When the micro-graphite powder falls off normally or contacts a small amount of water, it can enhance the self-lubricating effect of the modified polyetheretherketone and further reduce the friction resistance. Since the inner wall of the inner sleeve 042 has a very outstanding lubricity, it is not necessary to apply any other lubricating material, which not only keeps the inner cavity clean and stable, but also provides sufficient space for the balance spring 03.

[0040] After the support device 04 is screwed into the base 06, in order to further strengthen the connection between the support device 04 and the base 06, a locking nut 07 is also provided on the support device 04. The external thread on the support device 04 is exposed when the support device 04 is screwed into the base 06. The locking nut 07 is tightly connected to the above-mentioned exposed external thread. The locking nut 07 abuts against the surface of the base 06 to increase the pre-tightening force between the support device 04 and the base 06, so that the connection between the support device 04 and the base 06 is more secure.

[0041] Reference Figure 4 The present application can be applied to measuring the liquid level in a closed tank body 08, such as tank-type liquefied natural gas, liquid hydrogen and liquid oxygen, etc. The liquid to be detected is contained in the tank body 08, and the upper part of the tank body 08 is connected to a first pressure transmission pipeline 091, and a first isolation valve 0911 is arranged at the connection between the first pressure transmission pipeline 091 and the tank body 08. The first pressure transmission pipeline 091 can transmit the isolated gas pressure to the differential pressure transmitter, and the bottom of the tank body 08 is connected to a second pressure transmission pipeline 092, and a second isolation valve 0921 is arranged between the second pressure transmission pipeline 092 and the tank body 08. The second pressure transmission pipeline 092 is used to transmit the liquid pressure to the differential pressure transmitter.

[0042] The barrier composed of the balancing diaphragm 02 and the rubber bellows 05 separates the chamber of the shell 01 into a first chamber 011 and a second chamber 012. A first pressure input connector is provided in the first chamber 011, and the first pressure input connector is used to be connected to the first pressure transmission pipeline 091 of the tank body 08 to be detected, so that the gas pressure in the tank body 08 can be transmitted to the first chamber 011 through the first transmission pipeline; a second pressure input connector is provided in the second chamber 012, and the second pressure input connector is used to be connected to the second pressure transmission pipeline 092, so that the liquid pressure in the tank body 08 can be transmitted to the second chamber 012 through the second transmission pipeline.

[0043] During the detection process, the first pressure input connector is connected to the gas pressure in the tank body 08 to be detected, and the second pressure input connector is connected to the liquid pressure in the tank body 08. 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 02 are subjected to unbalanced air pressure and move to the side with lower air pressure. The differential pressure transmitter can obtain the liquid level of the detected liquid by converting the displacement of the balancing diaphragm 02. Since the balancing diaphragm 02 will shake under the impact of gas and affect the measurement result, the supporting device 04 can support the balancing spring 03. When the balancing diaphragm 02 is impacted by gas, the supporting device 04 can reduce the swing range of the balancing diaphragm 02 by limiting the movable range of the balancing spring 03. When the balancing diaphragm 02 is impacted by gas, the swing of the balancing diaphragm 02 can be reduced, thereby improving the measurement accuracy and reducing the possibility of damage to the balancing diaphragm 02 due to excessive swinging amplitude. The gap between the relative support devices 04 can be adjusted, so that the support device 04 can adjust the displacement range of the balancing diaphragm 02 while limiting the displacement of the balancing diaphragm 02, and the support device 04 can adapt to housings 01 and balancing springs 03 of different sizes, thereby improving the adaptability of the support device 04.

[0044] 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.

[0045] 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.

[0046] 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 011 through the first pressure input connector, and the liquid pressure P2 in the tank is transmitted to the second chamber 012 through the second pressure input connector. The gas pressure P1 acts on one side of the balancing diaphragm 02, and the liquid pressure P2 acts on the other side of the balancing diaphragm 02. Since the gas pressure P1 and the liquid pressure P2 act in opposite directions, the displacement of the balancing diaphragm 02 can output the effect of P=P2-P1, and the movement range of the balancing diaphragm 02 between the first chamber 011 and the second chamber 012 depends on the size of the gas pressure P1 and the liquid pressure P2.

[0047] In the embodiments of this application, refer to Figure 1The balancing diaphragm 02 is connected to a displacement link 11, and an output hole for the displacement link 11 to pass through is opened on the shell 01. One end of the displacement link 11 is connected to the balancing diaphragm 02, and the other end passes through the output hole and is connected to a display device 13 arranged outside the shell 01. A connecting ring is arranged between the displacement link 11 and the display device 13. The displacement link 11 can transmit the displacement of the balancing diaphragm 02 to the outside of the cavity and transmit it to the display device 13 through the connecting ring. The display device 13 can be a displacement display. A sealing device 12 is arranged at the connection position of the displacement link 11 with the output hole. The sealing device 12 can be a rubber ring, which is fixedly connected to the displacement link 11. The length of the rubber ring is greater than the displacement length of the displacement link 11. When the displacement link 11 is displaced, the rubber ring can always maintain close contact with the output hole to prevent the air pressure in the shell 01 from leaking.

[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 differential pressure transmitter, characterized in that: A support device (04) including a balancing spring (03), characterized in that it comprises: an inner sleeve (042) and a balancing spring (03) arranged in the inner sleeve (042), wherein the balancing spring (03) extends from the inner sleeve (042), the extended portion being used to connect with the balancing diaphragm (02), the balancing spring (03) being in contact with the inner surface of the inner sleeve (042), and the inner sleeve (042) being made of polyetheretherketone; An inner side wall of the inner sleeve (042) is provided with an embedding groove (0421), and graphite powder is embedded in the embedding groove (0421); It also includes an outer sleeve (041) sleeved on the inner sleeve (042), wherein the outer sleeve (041) is made of copper; A hollow shell (01) is provided with at least one supporting device (04) on opposite inner side walls thereof, and the axes of the opposite supporting devices (04) 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 balancing diaphragm (02) is arranged at the gap; The portion of the balancing spring (03) in the supporting device (04) extending out of the inner sleeve (042) is connected to the balancing diaphragm (02); A base (06) is provided between the outer sleeve (041) and the inner wall; The base (06) is provided with a groove, the side wall of the groove has a thread, the outer sleeve (041) is threadedly connected to the base (06), and the outer sleeve (041) can be rotated to adjust the distance between two opposing support devices (04); A gasket (10) is arranged inside the inner sleeve (042), and the gasket (10) is used to adjust the length of the balance spring (03) extending out of the inner sleeve (042).

2. The differential pressure transmitter according to claim 1, characterized in that: On an inner side wall of the shell (01), connection points between the support device (04) and the inner side wall are distributed on a circle.

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