A multi-mode ultra-high-precision back-pressure valve applicable to multiple pressure conditions

Abstract

The present invention provides a multi-mode ultra-high-precision back-pressure valve applicable to various pressure conditions, which mainly consists of an upper flange, a lower flange, a piston, a force equalizing plate, a diaphragm, a support ball, a sealing ring, etc. The upper flange and the lower flange are fixed by screws and sealed with a sealing ring. A diaphragm is clamped between the upper and lower flanges. There are two inlets at the upper part of the upper flange, namely a high-pressure air inlet and a low-pressure liquid inlet. Gas or liquid is injected through the two inlets to establish back pressure. There is a sample inlet and a sample outlet on the lower flange. The sample inlet is connected to the sample injection pipeline, so that the liquid enters the diversion groove through the sample injection pipeline and applies pressure to the diaphragm. When the pressure is greater than the back pressure, the diaphragm is pushed open and then flows out of the back-pressure valve through two support diversion hubs. The present invention can be applicable to working conditions from low pressure to ultra-high pressure, and the back-pressure is stable, solving the problems of difficult control of low-pressure gas pressure and unstable pressure of the back-pressure valve.

Description

Technical Field

[0001] The present invention relates to a multi-mode ultra-high-precision back pressure valve applicable to low-pressure to ultra-high-pressure working conditions for indoor displacement experiments. Background Art

[0002] A back pressure valve is an indispensable device for core displacement experiments. Currently, there are mainly three types of back pressure valves at home and abroad, namely needle-type back pressure valves, piston-type back pressure valves, and diaphragm-type back pressure valves. The needle-type back pressure valve uses a steel sheet and a needle valve to control the back pressure. The disclosed patent CN202834241U uses a spring to assist the needle valve to control the back pressure. The spring is difficult to control and has low precision. When the pressure is too high, the needle has a small force-bearing area and is extremely easy to be damaged. The disclosed patent CN202082434U is a piston-type back pressure valve, which uses the movement of the piston to control the fluid in and out, and adopts a double-diaphragm buffer design to make the piston move more smoothly. However, the piston has a large thickness, low precision, and complex operation. The disclosed patent CN103912700B is a diaphragm-type back pressure valve, which uses back pressure to compress the diaphragm and multiple-stage sealing rings for soft sealing, and controls the fluid outflow through the deformation of the diaphragm. However, the frequent deformation of the diaphragm is easy to cause fatigue damage, and under long-term pressure, the diaphragm will permanently deform. In addition, due to the compressibility of gas, most back pressure valves can only accurately control the pressure under high pressure, and it is difficult to control the gas pressure under low pressure, resulting in fluid escaping from the back pressure valve. Therefore, in order to solve the above problems, a multi-mode ultra-high-precision back pressure valve applicable to various pressure working conditions is designed. Summary of the Invention

[0003] The present invention provides a multi-mode ultra-high-precision back pressure valve applicable to various pressure working conditions, which has reliable sealing, is easy to install, and can avoid the problems of frequent diaphragm damage, outlet blockage, and unstable back pressure valve pressure. To achieve the above purposes, the following technical solutions are adopted:

[0004] A multi-mode ultra-high-precision back-pressure valve applicable to multiple pressure conditions, mainly composed of an upper flange, a lower flange, a piston, a force-equalizing plate, a diaphragm, a support ball, a sealing ring, etc. The upper flange and the lower flange are fixed by screws and sealed with a sealing ring. A diaphragm is clamped between the upper and lower flanges. There are two inlets on the upper part of the upper flange. One is a high-pressure air inlet. When the required pressure of the back-pressure valve is relatively high, gas enters the air chamber through the high-pressure air inlet for pressurization. The other is a low-pressure liquid inlet. When the required pressure is relatively low, liquid enters from here to push the piston. There is a protruding part on the force-equalizing plate that contacts the piston. There is a sealing ring on the piston to ensure that the liquid does not enter the air chamber. The piston squeezes the force-equalizing plate downward and presses the diaphragm tightly to prevent the liquid from overflowing. There is a sample inlet and a sample outlet on the lower flange. The sample inlet is connected to the sample injection pipeline, so that the liquid enters the diversion groove through the sample injection pipeline and applies pressure to the diaphragm. There are four sample injection pipelines, which can ensure that the fluid flows into the back-pressure valve evenly without causing blockage. The diversion groove is a structure of an I-shaped shape surrounded by a circle. Such a design can ensure that there are no extra gaps in the diaphragm and the sealing is good. When the pressure is greater than the back-pressure, the diaphragm is pushed open and then flows out of the back-pressure valve through two support diversion hubs.

[0005] The support diversion hub is a hollow cylinder with an arc-shaped outer periphery. There is a centering sleeve in the middle part that can center the diaphragm. The center is a square hole, and a support ball is placed inside. The support ball is made of bearing steel and has a relatively high hardness, which can support the diaphragm and prevent it from being damaged due to excessive deformation. Since the support ball is in the square hole, the fluid can flow into the sample outlet pipeline from the gap between the support ball and the square hole. The lower part of the lower flange is the sample outlet, and two sample outlet pipelines on it are connected to two support diversion hubs. The purpose of setting two support diversion hubs is to support the diaphragm. When the pressure difference is too large, the support ball and the sealing ring can keep the deformation amplitude of the diaphragm not too large, and the stress can be dispersed in the two support diversion hubs to avoid stress concentration. In addition, setting two can also ensure that the fluid is always continuous. When one hole is blocked, the other hole can still work normally to enable the experiment to continue.

[0006] When the back pressure required in the experiment is relatively low, since it is difficult to control the pressure of the gas at low pressure, a low-pressure liquid inlet is used to inject liquid to increase the pressure. The liquid squeezes the piston, and the piston further squeezes the equalizing plate. The equalizing plate applies the pressure on the diaphragm, thereby blocking the sampling pipeline. The fluid cannot flow out because the back pressure is greater than the fluid pressure. When it is necessary to discharge the fluid, the fluid pressure is increased to be greater than the back pressure. The fluid flows out from the sampling pipeline, gradually covers the diversion groove, and then pushes the diaphragm open. The fluid starts to flow on the lower flange plane and finally flows into the support diversion hub. Since the support ball is in the square hole, the fluid can flow into the sample outlet pipeline from the gap between the support ball and the square hole and finally flow out of the back pressure valve. When the back pressure required in the experiment is medium pressure, the high-pressure air inlet and the low-pressure liquid inlet are opened at the same time. The liquid maintains the lowest pressure and remains stable. The volatility of the gas causes the pressure to gradually change, so that the back pressure can be gradually and stably increased. When the back pressure required in the experiment is relatively high, due to the strong compressibility of the gas and the good elasticity of the gas at high pressure, a high-pressure air inlet is selected to inject gas to build pressure. After the gas is compressed into the air chamber, it directly contacts the diaphragm through two small holes on the equalizing plate. The gas applies the pressure on the equalizing plate, and the equalizing plate then squeezes the diaphragm to complete the sealing. When it is necessary to drain the liquid, it is the same as in the low-pressure case. The fluid enters the diversion groove, pushes the diaphragm open, and flows into the sample outlet pipeline and finally flows out of the back pressure valve. The purpose of doing this is to use liquid as the compression medium at low pressure. Through the movement of the piston, the pressure change can be better controlled, the pressure change can be kept stable, and the instantaneous pressure change will not be too large. When the pressure is greater than 1.6 MPa and less than 10 MPa, that is, when it is in the medium pressure range, a mixed mode of simultaneously opening the high-pressure air inlet and the low-pressure liquid inlet is adopted. The liquid maintains the lowest pressure and remains stable, while the gas causes the pressure to gradually change due to its volatility. By mixing the two, the pressure is gradually and stably increased. At high pressure, gas is used as the compression medium. Due to the good compressibility of the gas, the elasticity of the compressed gas at high pressure can keep the pressure relatively stable. When the pressure needs to be adjusted, the elasticity of the gas can also ensure that the pressure fluctuates within a certain range after the instantaneous pressure change is completed and finally stabilizes.

[0007] Compared with the existing back pressure valve, the present invention has the following advantages:

[0008] (1) It has two inlets, can be applied to working conditions with various pressures, and has high precision. When the pressure is high, the high-pressure air inlet is used; when the pressure is medium, the low-pressure liquid inlet and the high-pressure air inlet are opened simultaneously; when the pressure is low, the low-pressure liquid inlet is used, solving the problem of difficult control of low-pressure gas pressure. (2) It has two support and guide hubs, which can avoid problems such as pipeline blockage and stress concentration. (3) The support balls and the centering sleeves can, to a certain extent, slow down the fatigue damage and permanent deformation of the diaphragm. (4) The flow guide grooves can evenly distribute the fluid, making the pressure borne by each part of the diaphragm equal, and the diaphragm has a longer service life. (5) The sampling pipeline has four outlets, which can ensure the uniform entry of the fluid into the flow guide grooves. (6) The low-pressure and high-pressure modes help to keep the pressure in a relatively stable state all the time. Description of the Drawings

[0009] Figure 1 Front view of the back pressure valve

[0010] Figure 2 Right view of the back pressure valve

[0011] Figure 3 Top view of the back pressure valve

[0012] Figure 4 3D solid diagram of the support and guide hub

[0013] In the figure, 1. upper flange; 2. lower flange; 3. high-pressure air inlet; 4. low-pressure liquid inlet; 5. piston; 6. air chamber; 7. equalizing plate; 8. sealing ring; 9. diaphragm; 10. sampling port; 11. sampling pipeline; 12. support and guide hub; 13. support ball; 14. centering sleeve; 15. sample outlet pipeline; 16. sample outlet hole; 17. flow guide groove Detailed Implementation Modes

[0014] The back pressure valve will be further described below with reference to the attached drawings. A multi-mode ultra-high precision back pressure valve applicable to various pressure conditions mainly consists of an upper flange (1), a lower flange (2), a piston (5), a force equalizing plate (7), a diaphragm (9), a support ball (12), a sealing ring (8), etc. The upper flange (1) and the lower flange (2) are fixed by a screw rod (14). A diaphragm is clamped between the upper and lower flanges and sealed with a sealing ring (8). There are two inlets on the upper part of the upper flange. One is a high-pressure air inlet. When the required pressure of the back pressure valve is relatively high, gas enters the air chamber (6) through the high-pressure air inlet (3) for pressurization. The other is a low-pressure liquid inlet (4). When the required pressure is relatively low, liquid enters to push the piston (5). There is a protruding part on the force equalizing plate (7) that contacts the piston. There is a sealing ring on the piston to ensure that the liquid does not enter the air chamber. The piston squeezes the force equalizing plate downward and presses the diaphragm (9) tightly to prevent fluid from overflowing. When the experimental pressure is medium, both the high-pressure air inlet (3) and the low-pressure liquid inlet (4) are opened simultaneously. The liquid pushes the piston (5), and finally squeezes the thin plate to keep the pressure stable. Gas enters the air chamber (6). Due to the fluctuation of the gas, the pressure begins to change. Finally, through this mixed mode, the pressure gradually rises steadily. There is a sample inlet (10) and a sample outlet (16) on the lower flange (2). The sample inlet is connected to a sample inlet pipe (11), so that the liquid enters the diversion groove (17) through the pipe and applies pressure to the diaphragm. There are four sample inlet pipes, which can prevent the fluid from being too viscous and blocking the channel, and keep the fluid entering the diversion groove evenly. The diversion groove is a structure of an I-shaped shape surrounded by a circle. The purpose of this design is to ensure that there is no extra gap in the diaphragm and the sealing is good. There are two grooves on the lower flange, and inside the grooves are support diversion hubs (12). When the pressure is greater than the back pressure, the diaphragm is pushed open and then flows out of the back pressure valve through the two support diversion hubs (12).

[0015] The support diversion hub (12) is a hollow cylinder with an arc-shaped outer periphery. There is a centering sleeve (14) in the middle part that can center the diaphragm to prevent the diaphragm from deforming excessively. In the exact center is a square hole, and inside it is placed a support ball (13) to support the diaphragm and prevent it from being damaged due to excessive deformation. Since the support ball is in the square hole, fluid can flow into the sample outlet pipe (15) through the gap between the support ball and the square hole; at the lower part of the lower flange is the sample outlet (16), and two sample outlet pipes (15) on it are connected to the two support diversion hubs (12). The purpose of setting two support diversion hubs is to support the diaphragm. When the pressure difference is too large, the support ball and the sealing ring can keep the deformation amplitude of the diaphragm not too large, and the stress can be dispersed in the two support diversion hubs to avoid stress concentration. In addition, setting two can also ensure that the fluid is always continuous. When one hole is blocked, the other hole can still work normally to enable the experiment to continue.

[0016] When installing the back pressure valve, first place the diaphragm in the appropriate position on the lower flange, ensuring that it is centered and completely covers the four sampling pipes. Then install the piston on the upper flange, place the upper protrusion of the equalizing piece in contact with the piston so that it can be pressed tightly due to the movement of the piston. Install the upper flange so that the diaphragm is clamped and fixed by the upper and lower flanges. Use screws to fix the upper and lower flanges, and then connect the back pressure valve to the displacement experiment.

[0017] During the experiment, when the required back pressure in the experiment is relatively low, since it is difficult to control the pressure of the gas at low pressure, liquid is injected through the low-pressure liquid inlet (4) to increase the pressure. The liquid pushes the piston (5), and the piston further squeezes the equalizing piece (7). The equalizing piece applies the pressure on the diaphragm (9), thereby blocking the sampling pipe (11). The fluid cannot flow out because the back pressure is greater than the fluid pressure. When it is necessary to discharge the fluid, increase the fluid pressure to be greater than the back pressure. The fluid flows out from the sampling pipe, gradually covers the diversion groove (17), then pushes the diaphragm open, and the fluid starts to flow on the lower flange plane and finally flows into the support diversion hub (12), enters the sample outlet pipe (15) through the square hole and flows out of the back pressure valve. When the required pressure is medium pressure (1.6 MPa - 10 MPa), open the high-pressure air inlet and the low-pressure liquid inlet simultaneously. The liquid maintains the lowest pressure stability, while the gas pressure gradually changes due to its fluctuation. The pressure is gradually and stably increased through the mixing of the two. When the required back pressure in the experiment is relatively high, due to the strong compressibility of the gas and the good elasticity of the gas under high pressure, the high-pressure air inlet (3) is selected to inject gas to build pressure. After the gas is compressed into the air chamber (6), it directly contacts the diaphragm through the two small holes on the equalizing piece. The gas squeezes the equalizing piece, and the equalizing piece then applies the pressure on the diaphragm to finally complete the sealing. When it is necessary to drain the liquid, it is the same as when the pressure is low. The fluid enters the diversion groove, pushes the diaphragm open, flows into the sample outlet pipeline (15), and finally flows out of the back pressure valve.

[0018] In the back pressure valve, the upper and lower flanges are made of alloy steel, with low material cost and simple process; the support ball is made of bearing steel, with high hardness and can support the diaphragm; the sealing ring and the centering sleeve are made of polytetrafluoroethylene, with good sealing effect and not easy to deform; the equalizing piece and the diaphragm are both made of special alloy materials, with good elasticity, wear resistance and not easy to deform.

[0019] The present invention is not limited to the above embodiments. For those skilled in the art, various changes can be made to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A multi-mode ultra-high-precision back-pressure valve applicable to multiple pressure conditions, mainly composed of an upper flange, a lower flange, a piston, a force equalizing plate, a diaphragm, a support ball, a sealing ring, etc. The upper flange and the lower flange are fixed by screws and sealed with a sealing ring. A diaphragm is clamped between the upper and lower flanges; there are two inlets on the upper part of the upper flange. One is a high-pressure air inlet. When the required pressure of the back-pressure valve is relatively high, gas enters the air chamber through the high-pressure air inlet for pressurization. The other is a low-pressure liquid inlet. When the required pressure is relatively low, liquid enters here to push the piston. There is a protruding part on the force equalizing plate that contacts the piston. There is a sealing ring on the piston to ensure that the liquid does not enter the air chamber. The piston squeezes the force equalizing plate downward and presses the diaphragm tightly to prevent liquid overflow; there is a sampling inlet and a sampling outlet on the lower flange. The sampling inlet is connected to the sampling pipeline, so that the liquid enters the diversion groove through the sampling pipeline and applies pressure to the diaphragm. There are four sampling pipelines, which can ensure that the fluid flows into the back-pressure valve evenly without blockage. The diversion groove is a structure of an I-shaped surrounded by a circle. Such a design can ensure that there are no extra gaps in the diaphragm and the sealing is good. When the pressure is greater than the back-pressure, the diaphragm is pushed open and then flows out of the back-pressure valve through two support diversion hubs. The lower part of the lower flange is the sampling outlet, and two sampling pipelines on it are connected to the two support diversion hubs. The support diversion hub is a hollow cylinder, with an arc on the periphery. There is a centering sleeve in the middle part to center the diaphragm. The center is a square hole, and a support ball is placed inside. The support ball is made of bearing steel and has a high hardness, which can support the diaphragm and prevent it from being damaged due to excessive deformation. Since the support ball is in the square hole, the fluid can flow into the sampling pipeline from the gap between the support ball and the square hole.

2. The multi-mode ultra-high-precision back-pressure valve applicable to multiple pressure conditions according to claim 1, wherein The support diversion hub can support the diaphragm. When the pressure difference is too large, the support ball and the sealing ring can keep the deformation amplitude of the diaphragm not too large.

3. The multi-mode ultra-high precision back pressure valve applicable to multiple pressure conditions according to claim 1, characterized in that, There are two support diversion hubs, and the stress can be dispersed in the two support diversion hubs to avoid stress concentration. In addition, setting two can also ensure that the fluid is always continuous. When one hole is blocked, the other hole can still work normally to enable the experiment to continue.

4. The multi-mode ultra-high-precision back-pressure valve applicable to multiple pressure conditions according to claim 1, wherein It has two inlets, can be applicable to working conditions from low pressure to ultra-high pressure, and has a high precision. When the pressure is high, the high-pressure air inlet is used. When the pressure is low, the low-pressure liquid inlet is used. When the pressure is medium, the low-pressure liquid inlet and the high-pressure air inlet are opened simultaneously.

5. The multi-mode ultra-high-precision backpressure valve applicable to multiple pressure conditions according to claim 1, characterized in that The I-shaped diversion groove surrounded by a circle makes the fluid evenly distributed, so that the pressure borne by each part of the diaphragm is equal, and the service life of the diaphragm is longer.

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