Two-position three-way reversing valve and reversing method for small-flow liquid nitrogen cryogenic system

Abstract

The application provides a two-position three-way reversing valve for a small-flow liquid nitrogen cryogenic system and a reversing method. The two-position three-way reversing valve for the small-flow liquid nitrogen cryogenic system comprises a valve body structure, the valve body structure comprising a valve seat, an upper conical surface sealing seat, a lower conical surface sealing seat and a double-cone movable valve rod. By switching the double-cone movable valve rod to block and open the upper conical surface sealing seat and the lower conical surface sealing seat, the reversing of the ultralow-temperature fluid is realized by using the principle of the stop valve. The two-position three-way reversing valve for the small-flow liquid nitrogen cryogenic system has the characteristics of small volume, less cold loss, small leakage and fast response.

Description

[0001] This case is a divisional application of Chinese patent CN201711397157.2, a two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system and a reversing method. Technical Field

[0002] The present invention relates to a reversing valve, in particular to a two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system and a reversing method. Background Art

[0003] The current market is flooded with valves of many varieties and specifications, such as hydraulic valves, pneumatic valves, vacuum valves, and chemical valves. However, these valves are usually only suitable for use in room temperature environments and cannot be used in ultra-low temperature environments. Therefore, they cannot meet people's use needs in ultra-low temperature environments, for example, they cannot be used in cryoablation minimally invasive surgical systems. Summary of the Invention

[0004] In view of the defects of the prior art, the present invention provides a two-position three-way reversing valve and a reversing method for a small-flow liquid nitrogen cryogenic system, which can effectively solve the above problems.

[0005] The technical solution adopted in the present invention is as follows:

[0006] The present invention provides a two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system is an electromagnet-driven single-electrically controlled lever bellows valve, comprising: a valve body structure, a bellows sealing structure, a lever hinge force-increasing structure, and an electromagnet force-generating structure.

[0007] The valve body structure includes a valve seat, a double-cone movable valve stem, an upper conical sealing seat, a lower conical sealing seat and a movable valve core connecting rod;

[0008] A liquid inlet chamber is axially arranged at the center of the valve seat, and the left center of the liquid inlet chamber is connected to the liquid inlet; an upper liquid outlet and a lower liquid outlet are symmetrically arranged on the right side of the liquid inlet chamber; the upper liquid outlet is connected to the upper liquid outlet; and the lower liquid outlet is connected to the lower liquid outlet.

[0009] The upper conical sealing seat is fixedly and sealedly arranged at the upper part of the liquid inlet chamber; the lower conical sealing seat is symmetrically arranged at the lower part of the liquid inlet chamber; the upper conical sealing seat and the lower conical sealing seat are respectively provided with an upper sealing seat hole and a lower sealing seat hole at the axis thereof;

[0010] The double-cone movable valve stem includes an integrally formed double-cone sealing core head, an upper valve stem and a lower valve stem; the double-cone sealing core head is located in the liquid inlet chamber between the upper conical sealing seat and the lower conical sealing seat, the upper valve stem passes through the upper sealing seat hole of the upper conical sealing seat, and the outer diameter of the upper valve stem is smaller than the aperture of the upper sealing seat hole, so that a first upper gap flow channel is formed between the upper valve stem and the upper sealing seat hole, one end of the first upper gap flow channel is connected to the liquid inlet, and the first upper gap flow channel The other end is connected to the upper liquid outlet; and the double-cone sealing core head has an upper sealing cone surface, which is adapted to the upper sealing seat cone surface at the bottom of the upper conical sealing seat. When the double-cone sealing core head moves upward and is in close contact with the upper conical sealing seat, the passage between the liquid inlet and the first upper gap flow channel is cut off, thereby cutting off the upper liquid outlet; when the double-cone sealing core head moves downward away from the upper conical sealing seat, the liquid inlet, the first upper gap flow channel and the upper liquid outlet are connected;

[0011] The lower valve stem is symmetrically arranged with the upper valve stem; the lower valve stem passes through the lower sealing seat hole of the lower conical sealing seat, and the outer diameter of the lower valve stem is smaller than the aperture of the lower sealing seat hole, so that a first lower gap flow channel is formed between the lower valve stem and the lower sealing seat hole, one end of the first lower gap flow channel is connected with the liquid inlet, and the other end of the first lower gap flow channel is connected with the lower liquid outlet; and the double-cone sealing core head has a lower sealing cone surface, which is adapted to the lower sealing seat cone surface at the bottom of the lower conical sealing seat. When the double-cone sealing core head moves downward and tightly against the lower conical sealing seat, the passage between the liquid inlet and the first lower gap flow channel is cut off, and then the lower liquid outlet is cut off; when the double-cone sealing core head moves upward away from the lower conical sealing seat, the liquid inlet, the first lower gap flow channel and the lower liquid outlet are connected;

[0012] The bellows sealing structure includes a bellows and an elastic connector; the lever hinge force amplification structure includes a first transmission piston, a force amplification connecting rod and a second transmission piston;

[0013] The top of the upper valve stem of the double-conical movable valve stem is fixedly connected to one end of the movable valve core connecting rod; the other end of the movable valve core connecting rod is connected to one end of the elastic connector; the other end of the elastic connector is fixed to the first transmission piston; the bellows is fixedly sleeved on the outside of the movable valve core connecting rod;

[0014] The second transmission piston and the first transmission piston are arranged opposite to each other on the left and right; the two ends of the force-amplifying connecting rod are respectively fixed to the second transmission piston and the first transmission piston to form a lever structure; when the second transmission piston moves upward, the first transmission piston is driven downward by the force-amplifying connecting rod; and when the first transmission piston moves downward, the double-cone movable valve stem is driven downward by the elastic connector and the movable valve core connecting rod, thereby closing the lower liquid outlet and opening the upper liquid outlet; when the second transmission piston moves downward, the first transmission piston is driven upward by the force-amplifying connecting rod; and when the first transmission piston moves upward, the double-cone movable valve stem is driven upward by the elastic connector and the movable valve core connecting rod, thereby opening the lower liquid outlet and closing the upper liquid outlet;

[0015] The electromagnet force generating structure is used to generate a driving force to drive the second transfer piston to move upward or downward.

[0016] Preferably, the bellows sealing structure also includes a support sleeve; the support sleeve is sleeved on the outside of the bellows, the elastic connector and the movable valve core connecting rod; the bottom end of the support sleeve is fixedly connected to the valve seat; the top of the support sleeve is fixedly connected to the support structure for installing the first transmission piston.

[0017] Preferably, the electromagnet force generating structure includes a movable electromagnetic magnetized iron core, an electromagnetic coil, a fixed electromagnetic magnetized iron core, a connecting rod, a compression spring and a mounting structure;

[0018] The mounting structure has an interior of the mounting chamber; the second transmission piston is slidably mounted in the mounting chamber; the compression spring is disposed in the mounting chamber and above the second transmission piston; when the electromagnetic coil is de-energized, the pressure of the compression spring pushes the second transmission piston downward;

[0019] The connecting rod is arranged in the installation chamber and is located below the second conduction piston; the top of the connecting rod is connected to the second conduction piston; the bottom of the connecting rod is connected to the movable electromagnetic magnetized iron core; the fixed electromagnetic magnetized iron core is fixedly arranged below the movable electromagnetic magnetized iron core; the movable electromagnetic magnetized iron core and the fixed electromagnetic magnetized iron core are both located inside the electromagnetic coil; when the electromagnetic coil is energized, since the movable electromagnetic magnetized iron core and the fixed electromagnetic magnetized iron core have the same polarity, the repulsive force pushes the movable electromagnetic magnetized iron core upward, thereby pushing the second conduction piston upward through the connecting rod.

[0020] Preferably, the valve body structure further comprises an upper valve stem guide piston ring and a lower valve stem guide piston ring;

[0021] The upper valve stem guide piston ring is arranged in the liquid inlet chamber and is located above the upper conical sealing seat; the lower valve stem guide piston ring is arranged in the liquid inlet chamber and is located below the lower conical sealing seat; the top of the double-conical movable valve stem passes through the upper sealing seat hole and extends to the annular hole of the upper valve stem guide piston ring; the bottom of the double-conical movable valve stem passes through the lower sealing seat hole and extends to the annular hole of the lower valve stem guide piston ring.

[0022] Preferably, the valve body structure is made of stainless steel material with thermal conductivity lower than a threshold value.

[0023] Preferably, the bellows adopts a stainless steel metal bellows structure.

[0024] The present invention also provides a reversing method based on a two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system, comprising the following steps:

[0025] Step 1: When the electromagnetic coil is energized, the movable electromagnetic core and the fixed electromagnetic core have the same polarity and like poles repel each other. Therefore, the repulsive force pushes the movable electromagnetic core upward, thereby pushing the second conductive piston upward through the connecting rod.

[0026] When the second transmission piston moves upward, the electromagnetic force is amplified by the force-amplifying connecting rod, thereby exerting a greater force on the downward force of the first transmission piston. This amplified downward force quickly and forcefully pushes the first transmission piston downward. When the first transmission piston moves downward, it pushes the movable valve core connecting rod downward through the elastic connector used to mitigate radial force, thereby pushing the double-cone movable valve stem downward. When the double-cone movable valve stem moves downward, it forcefully abuts against the lower conical sealing seat, cutting off the passage between the liquid inlet and the lower liquid outlet, and opening the passage between the liquid inlet and the upper liquid outlet.

[0027] Step 2: When the electromagnetic coil is powered off, the repulsive force between the movable electromagnetic magnetized iron core and the fixed electromagnetic magnetized iron core disappears, and the pressure of the compression spring pushes the second conductive piston downward;

[0028] When the second transmission piston moves downward, the pressure of the compression spring is amplified by the action of the force-amplifying connecting rod, thereby generating a greater effect on the upward action of the first transmission piston; the amplified upward force quickly and forcefully drives the first transmission piston upward; when the first transmission piston moves upward, it drives the movable valve core connecting rod upward through the elastic connector used to alleviate the radial force, and then drives the double-cone movable valve stem upward; and when the double-cone movable valve stem moves upward, the double-cone movable valve stem forcefully clings to the upper conical sealing seat, cutting off the passage between the liquid inlet and the upper liquid outlet, and connecting the passage between the liquid inlet and the lower liquid outlet, thereby realizing the reversing function of the reversing valve.

[0029] The two-position three-way reversing valve and reversing method for a low-flow liquid nitrogen cryogenic system provided by the present invention have the following advantages:

[0030] The present invention is suitable for use in ultra-low temperature environments, especially in low-temperature environments with small flow rates. Utilizing the shut-off valve principle, the reversal of ultra-low temperature fluids is achieved by switching the double-cone movable valve stem to seal and open the upper conical sealing seat and the lower conical sealing seat. The two-position three-way reversing valve of the low-flow liquid nitrogen cryogenic system of the present invention has the characteristics of small size, small cold loss, small leakage and fast response, and has excellent performance. The present invention is a design for the internal piping system of a cryoablation minimally invasive surgical system, which improves the cold-heat conversion efficiency of the cryoablation minimally invasive surgical system and lays the foundation for further promoting cryoablation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic cross-sectional view of the structure of a two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system provided by the present invention. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] In the description of the present invention, it should be noted that the terms "front", "rear", "up" and "down" are determined based on the specific usage habits of the low-flow liquid nitrogen low-temperature two-position three-way reversing valve. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0034] The present invention provides a two-position, three-way reversing valve and a reversing method for a low-flow liquid nitrogen cryogenic system. The valve is an ultra-low-temperature, low-flow liquid nitrogen reversing valve that is very suitable for the valve box of a cryoablation minimally invasive surgical system. It can realize the functions of an existing reversing valve, but the valve body structure of the low-flow liquid nitrogen low-temperature, two-position, three-way reversing valve of the present invention is smaller in volume, making it suitable for use in ultra-low-temperature environments, especially in low-flow, low-temperature environments. Through the lever force-amplifying effect, it can also ensure a reliable and rapid reversing effect of the reversing valve, and has excellent performance. The present invention is designed for an internal piping system of a cryoablation minimally invasive surgical system, improves the cold-heat conversion efficiency of the cryoablation minimally invasive surgical system, and lays the foundation for further promotion of cryoablation technology.

[0035] refer to Figure 1The two-position, three-way directional valve used in low-flow liquid nitrogen cryogenic systems is an electromagnet-driven, single-lever, bellows valve. It includes a compact valve body, a bellows seal, a lever-hinge force-enhancing mechanism, and an electromagnet-generating mechanism. The following describes each of these four components in detail:

[0036] (1) Valve body structure

[0037] The valve body structure of the present invention arranges two liquid outlet chambers of different passages up and down, with a liquid inlet chamber in the middle. It is connected to the two liquid outlet chambers through upper and lower conical sealing seats. The double-conical movable valve stem is placed in the middle liquid inlet chamber. When it moves upward or downward to block the seat hole of one conical sealing seat, it will open the seat hole of the other conical sealing seat, thereby switching the low-temperature liquid nitrogen working medium entering the valve body to the specified downstream channel pipeline as required.

[0038] Specifically, the valve body structure includes a valve seat 5, a double-cone movable valve stem 2, an upper conical sealing seat 1, a lower conical sealing seat 3 and a movable valve core connecting rod 7;

[0039] A liquid inlet chamber is axially arranged at the center of the valve seat 5, and the left center of the liquid inlet chamber is connected to the liquid inlet 16; the upper liquid outlet and the lower liquid outlet are symmetrically arranged on the right side of the liquid inlet chamber; the upper liquid outlet is connected to the upper liquid outlet 17; the lower liquid outlet is connected to the lower liquid outlet 18; therefore, the two-position three-way reversing valve has three external pipeline connection ports, namely the liquid inlet, the upper liquid outlet and the lower liquid outlet.

[0040] An upper conical sealing seat 1 is sealed and fixedly arranged at the upper part of the liquid inlet chamber; a lower conical sealing seat 3 is symmetrically arranged at the lower part of the liquid inlet chamber; an upper sealing seat hole and a lower sealing seat hole are respectively opened at the axis of the upper conical sealing seat 1 and the lower conical sealing seat 3; wherein, the material of the conical sealing seat is PTFE, and it is pressed and fixed in the valve seat positioning circular hole with a locking nut.

[0041] The double-cone movable valve stem 2 comprises a one-piece double-cone sealing core 2.1, an upper valve stem 2.2 and a lower valve stem 2.3; the double-cone sealing core 2.1 is located in the liquid inlet chamber between the upper conical sealing seat 1 and the lower conical sealing seat 3, the upper valve stem 2.2 passes through the upper sealing seat hole of the upper conical sealing seat 1, and the outer diameter of the upper valve stem 2.2 is smaller than the hole diameter of the upper sealing seat hole, so that the first upper gap flow channel is formed between the upper valve stem 2.2 and the upper sealing seat hole, one end of the first upper gap flow channel is communicated with the liquid inlet 16, and the other end of the first upper gap flow channel is communicated with the upper liquid outlet 17; and the double-cone sealing core 2.1 has an upper sealing cone surface which is matched with the upper sealing seat cone surface at the bottom of the upper conical sealing seat 1, when the double-cone sealing core 2.1 moves upward and tightly abuts against the upper conical sealing seat 1, the passage of the liquid inlet 16 and the first upper gap flow channel is cut off, and then the upper liquid outlet 17 is cut off; when the double-cone sealing core 2.1 moves downward and away from the upper conical sealing seat 1, the liquid inlet 16, the first upper gap flow channel and the upper liquid outlet 17 are communicated;

[0042] The lower valve stem 2.3 is symmetrically arranged with the upper valve stem 2.2; the lower valve stem 2.3 passes through the lower sealing seat hole of the lower conical sealing seat 3, and the outer diameter of the lower valve stem 2.3 is smaller than the hole diameter of the lower sealing seat hole, so that the first lower gap flow channel is formed between the lower valve stem 2.3 and the lower sealing seat hole, one end of the first lower gap flow channel is communicated with the liquid inlet 16, and the other end of the first lower gap flow channel is communicated with the lower liquid outlet 18; and the double-cone sealing core 2.1 has a lower sealing cone surface which is matched with the lower sealing seat cone surface at the bottom of the lower conical sealing seat 3, when the double-cone sealing core 2.1 moves downward and tightly abuts against the lower conical sealing seat 3, the passage of the liquid inlet 16 and the first lower gap flow channel is cut off, and then the lower liquid outlet 18 is cut off; when the double-cone sealing core 2.1 moves upward and away from the lower conical sealing seat 3, the liquid inlet 16, the first lower gap flow channel and the lower liquid outlet 18 are communicated. That is, the movable valve stem uses the principle of stop valve to block one sealing seat while opening another coaxially arranged sealing seat, so as to realize the purpose of liquid path reversing. In actual application, the sealing materials of the double-cone movable valve stem, the upper conical sealing seat and the lower conical sealing seat are required to be combined with soft and hard to obtain better sealing performance.

[0043] In addition, in order to obtain the accurate centering performance with the upper and lower conical sealing seats, the two ends of the double-cone movable valve stem are supported by double-guide piston rings, so as to ensure that the center axes of the double-cone movable valve stem and the conical sealing seats are consistent. That is, the valve body structure further comprises an upper valve stem guide piston ring 4 and a lower valve stem guide piston ring 19.

[0044] The upper valve stem guide piston ring 4 is arranged in the liquid inlet chamber and above the upper conical sealing seat 1, and the lower valve stem guide piston ring 19 is arranged in the liquid inlet chamber and below the lower conical sealing seat 3. The top of the double-cone movable valve stem 2 extends into the ring hole of the upper valve stem guide piston ring 4 after passing through the upper sealing seat hole, and the bottom of the double-cone movable valve stem 2 extends into the ring hole of the lower valve stem guide piston ring 19 after passing through the lower sealing seat hole.

[0045] The valve stem guide piston ring is made of wear-resistant bronze material, and is locked and fixed at both ends of the double-cone movable valve stem by a nut. The double-cone movable valve stem is made of 304 stainless steel material, and the outer conical surface is consistent with the inner hole conical surface of the sealing seat. After the double-cone movable valve stem is pressed against the sealing seat, the soft and hard deformation is adhered to achieve strict sealing and reduce the leakage of the reversing valve closed channel.

[0046] (II) Bellows sealing structure and lever hinge reinforcement structure

[0047] The bellows sealing structure includes a bellows 6 and an elastic connector 8. The elastic connector is made of 65Mn spring steel and is quenched to have high elasticity. In order to improve the elastic deformation capacity, the elastic connector is arranged with a wire-cutting transverse slit along the axis.

[0048] The lever hinge reinforcement structure includes a first transmission piston 9, a reinforcement connecting rod 11 and a second transmission piston 12.

[0049] The top of the upper valve stem 2.2 of the double-cone movable valve stem 2 is fixedly connected with one end of the movable valve core connecting rod 7. The other end of the movable valve core connecting rod 7 is connected with one end of the elastic connector 8. The other end of the elastic connector 8 is fixed with the first transmission piston 9. The bellows 6 is installed outside the movable valve core connecting rod 7. The bellows sealing structure further includes a support sleeve 20. The support sleeve 20 is sleeved outside the bellows 6, the elastic connector 8 and the movable valve core connecting rod 7. The bottom end of the support sleeve 20 is fixedly connected with the valve seat 5. The top of the support sleeve 20 is fixedly connected with a support structure for installing the first transmission piston 9.

[0050] The main function of the elastic connector is that the movable valve core connecting rod is composed of two to three short shafts, and the overall length is relatively long. If the elastic connector is not arranged, radial side force is easily generated during the up-down movement of the movable valve core connecting rod for valve reversing, so that the valve opening and closing is not smooth. Since the short shafts are connected by the elastic connector, the unnecessary radial force is unloaded while the axial force is maintained, so that the valve opening and closing is smooth.

[0051] The double-conical movable valve stem is externally connected to a longer movable valve core connecting rod, and its function is: since the reversing valve of the present invention is a reversing valve particularly suitable for use in ultra-low temperature liquid nitrogen environment, therefore, by setting a longer movable valve core connecting rod, the cold conduction path can be extended, and the environment heat is exchanged through the longer path, gradually changing from low temperature to normal temperature, without conducting the cold to the electromagnetic coil, thereby making it suitable for ultra-low temperature environment.

[0052] Furthermore, because the reversing valve of the present invention is particularly suitable for use in ultra-low temperature liquid nitrogen environments, conventional sealing gaskets are unsuitable for such environments. Therefore, the dynamic seal of the movable valve stem and its extended rod structure is a metal bellows structure seal. The stainless steel metal bellows of the valve are welded stainless steel bellows with good deformability. The metal bellows are 316L stainless steel welded bellows. One end of the metal bellows is welded to the movable valve core connecting rod. The other end of the metal bellows and the metal sealing gasket are compressed and fixed to the end face of the stainless steel valve seat with a locking nut. The inner cavity of the 316L stainless steel welded bellows and the inner cavity of the valve seat form a sealed chamber. The metal sealing gasket is a red copper gasket, thereby achieving a seal for the fluid medium.

[0053] The lever-hinged force-amplifying mechanism's primary function is to connect the movable valve stem to the electromagnetic core and spring structure via a lever. The lever mechanism acts as a force-amplifying structure, amplifying the electromagnetic and spring forces to meet the required compression and sealing force between the valve stem and the conical sealing seat.

[0054] Specifically, the second transmission piston 12 and the first transmission piston 9 are arranged opposite each other on the left and right sides; the two ends of the force-boosting connecting rod 11 are respectively fixed to the second transmission piston 12 and the first transmission piston 9 to form a lever structure; when the second transmission piston 12 moves upward, the first transmission piston 9 is driven downward by the force-boosting connecting rod 11; and when the first transmission piston 9 moves downward, the elastic connector 8 and the movable valve core connecting rod 7 drive the double-conical movable valve stem 2 downward, thereby closing the lower liquid outlet 18 and opening the upper liquid outlet 17; when the second transmission piston 12 moves downward, the first transmission piston 9 is driven upward by the force-boosting connecting rod 11; and when the first transmission piston 9 moves upward, the elastic connector 8 and the movable valve core connecting rod 7 drive the double-conical movable valve stem 2 upward, thereby opening the lower liquid outlet 18 and closing the upper liquid outlet 17.

[0055] (3) Electromagnet force structure

[0056] The electromagnet force generating structure is used to generate the driving force to drive the second transfer piston 12 upward or downward. The electromagnet force generating structure includes a movable electromagnetic magnetized iron core 13, an electromagnetic coil 14, a fixed electromagnetic magnetized iron core 15, a connecting rod 21, a compression spring 10, and a mounting structure.

[0057] The mounting structure has an interior mounting chamber; a second transmission piston 12 is slidably mounted in the mounting chamber; a compression spring 10 is disposed in the mounting chamber and above the second transmission piston 12; when the electromagnetic coil 14 is de-energized, the pressure of the compression spring 10 pushes the second transmission piston 12 downward.

[0058] A connecting rod 21 is disposed in the mounting chamber and is positioned below the second transfer piston 12. The top of the connecting rod 21 is connected to the second transfer piston 12, and the bottom of the connecting rod 21 is connected to the movable electromagnetic core 13. A fixed electromagnetic core 15 is fixedly disposed below the movable electromagnetic core 13. Both the movable electromagnetic core 13 and the fixed electromagnetic core 15 are positioned within the electromagnetic coil 14. When the electromagnetic coil 14 is energized, the repulsive force pushes the movable electromagnetic core 13 upward because the movable and fixed electromagnetic cores 13 and 15 have the same polarity, thereby pushing the second transfer piston 12 upward via the connecting rod 21.

[0059] To improve the operational accuracy and reliability of the low-flow liquid nitrogen cryogenic, two-position, three-way directional control valve mechanism of the present invention, the guide length of the second transfer piston (12) has been lengthened. By welding a guide ring beneath the second transfer piston, the guide length of the second transfer piston (12) is increased without significantly increasing the size and weight of the directional control valve. The welded guide ring of the second transfer piston is made of bronze.

[0060] The actuator and power mechanism of the present invention are connected by a lever mechanism, in which the lever acts as a force-amplifying structure, amplifying electromagnetic and spring forces to meet the required compression and sealing force between the valve stem and the conical sealing seat. In this structure, the two ends of the lever are respectively inserted into the gaps between the conductive pistons. The conductive piston of the power mechanism moves up and down, driving the lever to swing, causing the conductive piston of the actuator at the other end of the lever to also move up and down. This, in turn, drives the movable valve stem up and down through an elastic connector, closing or opening the sealing seats of the upper and lower channels, thus switching the fluid path. In this invention, the actuator is the movable valve stem motion structure; the power mechanism is a compression spring and electromagnet structure.

[0061] The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system of the present invention minimizes the mass of the valve body during structural design in order to reduce the cooling loss of the liquid nitrogen working medium caused by the valve body structure and reduce the volume and mass of the valve body structure. The valve body material is 304 stainless steel with poor thermal conductivity.

[0062] The present invention also provides a reversing method based on a two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system, comprising the following steps:

[0063] Step 1: When the electromagnetic coil 14 is energized, the movable electromagnetic core 13 and the fixed electromagnetic core 15 have the same polarity and like poles repel each other. Therefore, the repulsive force pushes the movable electromagnetic core 13 upward, thereby pushing the second conductive piston 12 upward through the connecting rod 21.

[0064] When the second transmission piston 12 moves upward, the electromagnetic force is amplified by the force-amplifying connecting rod 11, thereby exerting a greater force on the downward force of the first transmission piston 9. This amplified downward force quickly and forcefully pushes the first transmission piston 9 downward. When the first transmission piston 9 moves downward, it pushes the movable valve core connecting rod 7 downward through the elastic connector 8 for mitigating radial force, thereby pushing the double-cone movable valve stem 2 downward. When the double-cone movable valve stem 2 moves downward, it forcefully abuts the lower conical sealing seat 3, blocking the passage between the liquid inlet 16 and the lower liquid outlet 18, and opening the passage between the liquid inlet 16 and the upper liquid outlet 17.

[0065] Step 2: When the electromagnetic coil 14 is powered off, the repulsive force between the movable electromagnetic magnetized iron core 13 and the fixed electromagnetic magnetized iron core 15 disappears, and the pressure of the compression spring 10 pushes the second conductive piston 12 downward;

[0066] When the second transmission piston 12 moves downward, the pressure of the compression spring 10 is amplified by the action of the force-boosting connecting rod 11, thereby generating a greater force on the upward action of the first transmission piston 9; this amplified upward force quickly and forcefully drives the first transmission piston 9 upward; when the first transmission piston 9 moves upward, it drives the movable valve core connecting rod 7 upward through the elastic connector 8 for alleviating radial force, and then drives the double-cone movable valve stem 2 upward; and when the double-cone movable valve stem 2 moves upward, the double-cone movable valve stem 2 forcefully clings to the upper conical sealing seat 1, cutting off the passage between the liquid inlet 16 and the upper liquid outlet 17, and opening the passage between the liquid inlet 16 and the lower liquid outlet 18, thereby realizing the reversing function of the reversing valve.

[0067] It can be seen that the present invention provides a two-position three-way reversing valve that can be used for a small-flow liquid nitrogen low-temperature system in a cryoablation minimally invasive surgical system. Structurally, the valve body volume is smaller than the existing ultra-low-temperature valve volume, which reduces the cold loss of the liquid nitrogen mass caused by the valve body structure and improves the cold utilization efficiency of the cryoablation minimally invasive surgical system. Since a stop valve structure is used as the reversing valve, the leakage of the reversing valve is greatly reduced, and the cold-heat conversion efficiency of the cryoablation minimally invasive surgical system is improved, creating conditions for the promotion of cryoablation minimally invasive surgery.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system, characterized in that: The valve body structure includes: A valve seat (5), wherein a liquid inlet chamber is axially provided at the center of the valve seat (5), the left side of the liquid inlet chamber being in communication with the liquid inlet (16); an upper liquid outlet end and a lower liquid outlet end are respectively provided on the right side of the liquid inlet chamber; the upper liquid outlet end is in communication with the upper liquid outlet (17), and the lower liquid outlet end is in communication with the lower liquid outlet (18); An upper conical sealing seat (1) is arranged at the upper part of the liquid inlet chamber; a lower conical sealing seat (3), which is arranged at the lower part of the liquid inlet chamber; and A double-cone movable valve stem (2), the double-cone movable valve stem (2) passing through the liquid inlet chamber, when the double-cone movable valve stem (2) moves upward and abuts against the upper conical sealing seat (1), the liquid inlet (16) and the upper liquid outlet (17) are connected; when the double-cone movable valve stem (2) moves downward and abuts against the lower conical sealing seat (3), the liquid inlet (16) and the lower liquid outlet (18) are connected; The double-cone movable valve stem (2) comprises an integrally formed double-cone sealing core head (2.1), an upper valve stem (2.2) and a lower valve stem (2.3); the double-cone sealing core head (2.1) is located in a liquid inlet chamber between the upper conical sealing seat (1) and the lower conical sealing seat (3); The invention also includes a lever hinge force-amplifying structure, wherein the lever hinge force-amplifying structure includes a force-amplifying connecting rod (11), a first transmission piston (9) and a second transmission piston (12), wherein the first transmission piston (9) and the second transmission piston (12) are arranged on the left and right sides of the force-amplifying connecting rod (11) relative to each other, and the first transmission piston (9) and the second transmission piston (12) are respectively fixed to the two ends of the force-amplifying connecting rod (11) to form a lever structure; The top of the upper valve stem (2.2) of the double-cone movable valve stem (2) is connected to the first transmission piston (9); When the second transmission piston (12) moves upward, the force-amplifying connecting rod (11) drives the first transmission piston (9) to move downward, thereby driving the double-cone movable valve stem (2) to move downward, thereby enabling communication between the liquid inlet (16) and the upper liquid outlet (17); When the second transmission piston (12) moves downward, the force-amplifying connecting rod (11) drives the first transmission piston (9) to move upward, thereby driving the double-cone movable valve stem (2) to move upward, thereby enabling communication between the liquid inlet (16) and the lower liquid outlet (18); Also included is a bellows sealing structure, the bellows sealing structure comprising a bellows (6) and an elastic connector (8); The valve body structure further comprises a movable valve core connecting rod (7), the bellows (6) is fixedly sleeved on the outside of the movable valve core connecting rod (7), and the lower end of the elastic connector (8) is coaxially connected to the upper end of the valve core connecting rod (7); The top of the upper valve stem (2.2) of the double-cone movable valve stem (2) is connected to the first conducting piston (9) via the movable valve core connecting rod (7) and the elastic connector (8), and the elastic connector (8) is used to alleviate radial force.

2. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system according to claim 1, characterized in that: The upper valve stem (2.2) passes through an upper sealing seat hole formed at the axis of the upper conical sealing seat (1) and forms a first upper gap flow channel with the upper sealing seat hole, and the first upper gap flow channel is respectively connected to the liquid inlet (16) and the upper liquid outlet (17); The lower valve stem (2.3) passes through a lower sealing seat hole formed at the axis of the lower conical sealing seat (3) and forms a first lower gap flow channel with the lower sealing seat hole, and the first lower gap flow channel is respectively connected to the liquid inlet (16) and the lower liquid outlet (18); When the double-cone sealing core head (2.1) moves downward to move away from the upper conical sealing seat (1), the liquid inlet (16), the first upper gap flow channel and the upper liquid outlet (17) are connected; when the double-cone sealing core head (2.1) moves downward to be in close contact with the lower conical sealing seat (3), the connection between the liquid inlet (16), the first lower gap flow channel and the lower liquid outlet (18) is cut off; When the double-cone sealing core head (2.1) moves upward to move away from the lower conical sealing seat (3), the liquid inlet (16), the first lower gap flow channel and the lower liquid outlet (18) are connected; when the double-cone sealing core head (2.1) moves upward to be in close contact with the upper conical sealing seat (1), the connection between the liquid inlet (16), the first upper gap flow channel and the upper liquid outlet (17) is cut off.

3. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system according to claim 2, wherein the double-cone sealing core head (2.1) has an upper sealing cone surface and a lower sealing cone surface. in, The upper sealing conical surface is used to match the upper sealing seat conical surface at the bottom of the upper conical surface sealing seat (1), so that the double-conical surface sealing core head (2.1) can be closely attached to the upper conical surface sealing seat (1); The lower sealing conical surface is used to match the lower sealing seat conical surface at the bottom of the lower conical surface sealing seat (3), so that the double-conical surface sealing core head (2.1) can be closely attached to the lower conical surface sealing seat (3).

4. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system according to claim 2 or 3, characterized in that: The outer diameter of the upper valve stem (2.2) is smaller than the aperture of the upper sealing seat hole, so that the first upper gap flow channel is formed between the upper valve stem (2.2) and the upper sealing seat hole; The outer diameter of the lower valve stem (2.3) is smaller than the aperture of the lower sealing seat hole, so that the first lower gap flow channel is formed between the lower valve stem (2.3) and the lower sealing seat hole.

5. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system according to claim 1, characterized in that: The bellows sealing structure further comprises a support sleeve (20); the support sleeve (20) is sleeved on the outside of the bellows (6), the elastic connector (8) and the movable valve core connecting rod (7); the bottom end of the support sleeve (20) is fixedly connected to the valve seat (5); and the top of the support sleeve (20) is fixedly connected to a support structure for mounting the first transmission piston (9).

6. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system according to claim 1, characterized in that: The two-position three-way reversing valve used in the low-flow liquid nitrogen cryogenic system is a single-electrically controlled lever bellows valve driven by an electromagnet; The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system further comprises an electromagnet force generating structure, wherein the electromagnet force generating structure is used to generate a driving force for driving the second conducting piston (12) to move upward or downward; The electromagnet force generating structure comprises a movable electromagnetic magnetized iron core (13), an electromagnetic coil (14), a fixed electromagnetic magnetized iron core (15) and a compression spring (10); the fixed electromagnetic magnetized iron core (15) is fixedly arranged below the movable electromagnetic magnetized iron core (13), and the movable electromagnetic magnetized iron core (13) and the fixed electromagnetic magnetized iron core (15) are both located inside the electromagnetic coil (14); The compression spring (10) and the movable electromagnetic magnetized iron core (13) are respectively arranged above and below the second conduction piston (12), and are respectively connected to the second conduction piston (12); When the electromagnetic coil (14) is energized, the repulsive force between the movable electromagnetic magnetized iron core (13) and the fixed electromagnetic magnetized iron core (15) pushes the movable electromagnetic magnetized iron core (13) to move upward, thereby pushing the second conductive piston (12) to move upward; When the electromagnetic coil (14) is de-energized, the pressure of the compression spring (10) acts on the second conduction piston (12) and pushes the second conduction piston (12) to move downward.

7. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system according to claim 6, characterized in that: The electromagnet force generating structure further comprises a connecting rod (21) and a mounting structure, wherein the mounting structure has a mounting chamber inside; the second transmission piston (12) is slidably mounted in the mounting chamber, and the compression spring (10) and the connecting rod (21) are both arranged in the mounting chamber; The connecting rod (21) is located below the second conducting piston (12); the movable electromagnetic magnetized iron core (13) is connected to the second conducting piston (12) through the connecting rod (21).

8. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system according to claim 2 or 3, characterized in that: The valve body structure further comprises an upper valve stem guide piston ring (4), which is arranged in the liquid inlet chamber and located above the upper conical sealing seat (1); The top of the double-cone movable valve stem (2) passes through the upper sealing seat hole and extends into the ring hole of the upper valve stem guide piston ring (4).

9. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system according to claim 2 or 3, characterized in that: The valve body structure further comprises a lower valve stem guide piston ring (19), which is arranged in the liquid inlet chamber and located below the lower conical sealing seat (3); The bottom of the double-cone movable valve stem (2) passes through the lower sealing seat hole and extends into the ring hole of the lower valve stem guide piston ring (19).

10. The two-position three-way reversing valve for a low-flow liquid nitrogen cryogenic system according to any one of claims 1 to 3, characterized in that: The upper conical sealing seat (1) and the lower conical sealing seat (3) are made of PTFE, and the upper conical sealing seat (1) and the lower conical sealing seat (3) are respectively pressed and fixed in the positioning circular hole of the valve seat (5) by locking nuts; The double-cone movable valve stem (2) is respectively tightly attached to the upper conical sealing seat (1) and the lower conical sealing seat (3), and is sealed by means of soft and hard deformation.

11. A method for reversing a two-position three-way reversing valve used in a low-flow liquid nitrogen cryogenic system according to any one of claims 1 to 10, characterized in that: The following steps are involved: The power mechanism pushes the double-conical movable valve stem (2) of the valve body structure to move upward and abut against the upper conical sealing seat (1), so that the liquid inlet (16) and the upper liquid outlet (17) are connected, so that the liquid entering the valve body structure can flow out from the upper liquid outlet (17); or The power mechanism pushes the double-conical movable valve stem (2) of the valve body structure to move downward and abut against the lower conical sealing seat (3), thereby connecting the liquid inlet (16) and the lower liquid outlet (18), so that the liquid entering the valve body structure can flow out from the lower liquid outlet (18).

12. The commutation method according to claim 11, characterized in that: The power mechanism is an electromagnet force generating structure, and the electromagnet force generating structure comprises a movable electromagnetic magnetized iron core (13), an electromagnetic coil (14), a fixed electromagnetic magnetized iron core (15) and a compression spring (10); When the power mechanism pushes the double-cone movable valve stem (2) of the valve body structure to move upward and abut against the upper conical sealing seat (1), the electromagnetic force is amplified through the force-increasing connecting rod (11); When the power mechanism pushes the double-cone movable valve stem (2) of the valve body structure to move downward and abut against the lower conical sealing seat (3), the pressure effect of the compression spring (10) is amplified through the force-increasing connecting rod (11).

13. The commutation method according to claim 11 or 12, characterized in that: The power mechanism pushes the double-cone movable valve stem (2) of the valve body structure to move upward and abut against the upper conical sealing seat (1), including the following sub-steps: The electromagnetic coil (14) is de-energized; The pressure of the compression spring (10) pushes the second transmission piston (12) downward; The force-increasing connecting rod (11) connected to the second transmission piston (12) amplifies the pressure of the compression spring (10) to drive the first transmission piston (9) to move upward; The first transmission piston (9) drives the movable valve core connecting rod (7) to move upward through the elastic connector (8) for alleviating radial force; The movable valve core connecting rod (7) drives the double-cone movable valve stem (2) to move upward.

14. The commutation method according to claim 11 or 12, characterized in that: The power mechanism pushes the double-cone movable valve stem (2) of the valve body structure to move downward and abut against the lower conical sealing seat (3), including the following sub-steps: The electromagnetic coil (14) is energized; A repulsive force is generated between the movable electromagnetic magnetized iron core (13) and the fixed electromagnetic magnetized iron core (15), and the repulsive force pushes the movable electromagnetic magnetized iron core (13) to move upward; The movable electromagnetic magnetized iron core (13) pushes the second conducting piston (12) to move upwards through the connecting rod (21); The electromagnetic force is amplified by a force-amplifying connecting rod (11) connected to the second transmission piston (12) to push the first transmission piston (9) downward; The first transmission piston (9) pushes the movable valve core connecting rod (7) downward through the elastic connector (8) for alleviating radial force; The movable valve core connecting rod (7) pushes the double-cone movable valve stem (2) to move downward.

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