Low-temperature electrically adjustable regulating valve with adjustable pre-tension and method of regulating

Abstract

The application provides a low-temperature electric regulating valve with adjustable pre-tightening force and a regulating method. The low-temperature electric regulating valve with adjustable pre-tightening force comprises a valve body structure, a pre-tightening force regulating structure and a driving mechanism. The valve body structure comprises a valve body, a valve seat, a liquid inlet, a liquid outlet, a valve rod and a valve core. The pre-tightening force regulating structure comprises an elastic element mounting seat, an elastic element, a push rod pressing block, a push rod, a cover and a baffle. The advantages are that the sealing force between the valve core and the valve seat can be simply, quickly and accurately detected during the valve closing process, so that the sealing force between the valve core and the valve seat is controlled in the required range, the pre-tightening force of the regulating valve is changed from non-adjustable to adjustable, the pre-tightening force regulation for tightly combining the sealing surface of the valve seat and the valve core is more reasonable, the pre-tightening force is prevented from being too large or too small, the valve core wear is effectively reduced under the premise of meeting the leakage requirement, and the service life of the valve is prolonged.

Description

[0001] This application is a divisional application of application No. CN201711394676.3, with the invention name of "low-temperature electric regulating valve with adjustable pre-tightening force and adjusting method". TECHNICAL FIELD

[0002] The application belongs to the technical field of valves, and particularly relates to a low-temperature electric regulating valve with adjustable pre-tightening force and an adjusting method. BACKGROUND

[0003] At present, there are many kinds of regulating valves, and there are also many patents. However, the existing various regulating valves mainly have the following problems: when the regulating valve is closed, the sealing force between the valve seat and the valve core sealing surface cannot be detected, so the sealing force is often too large or too small. If the sealing force is too small, leakage is prone to occur; if the sealing force is too large, the valve core is easily worn, and the service life of the valve is reduced. Therefore, how to simply and effectively control the sealing force between the valve core and the valve seat, effectively reduce the wear of the valve core under the premise of meeting the leakage requirement, and improve the service life of the valve is an urgent problem to be solved at present. SUMMARY

[0004] In view of the defects in the prior art, the application provides a low-temperature electric regulating valve with adjustable pre-tightening force and an adjusting method, which can effectively solve the above problems.

[0005] The technical scheme adopted by the application is as follows:

[0006] The application provides a low-temperature electric regulating valve with adjustable pre-tightening force, which comprises a valve body structure, a pre-tightening force adjusting structure and a driving mechanism.

[0007] The valve body structure comprises a valve body, a valve seat, a liquid inlet, a liquid outlet, a valve rod and a valve core.

[0008] The pre-tightening force adjusting structure comprises an elastic member mounting seat, an elastic member, a push rod pressing block, a push rod, a cover and a baffle.

[0009] The driving mechanism is used for driving the push rod to perform linear lifting motion.

[0010] The driving mechanism is installed on the top of the cover; the bottom of the cover is provided with a threaded opening; the top end of the valve rod is sealingly and fixedly connected with the threaded opening of the cover; the bottom end of the valve rod is sealingly and fixedly connected with the opening of the valve body; the baffle is fixedly installed on the top of the threaded opening of the cover; the baffle and the inner cavity of the valve rod form a movement cavity; the top end of the push rod is located in the interior of the cover and connected with the driving mechanism; the bottom end of the push rod extends into the movement cavity through the baffle; the bottom end of the push rod has a stepped protrusion; the interior of the elastic member mounting seat has a cavity for placing the elastic member; the top of the elastic member mounting seat is screw-connected with the push rod pressing block to form an integral movement component; the integral movement component is provided with a stepped groove matched with the stepped protrusion; the integral movement component is hung on the stepped protrusion of the push rod through the stepped groove; at this time, the elastic member located in the interior of the elastic member mounting seat is located directly below the push rod, and the elastic member is initially in a compressed state and has a pre-tightening force.

[0011] The valve body is located below the valve rod; the valve body is provided with the liquid inlet and the liquid outlet; the interior of the valve body is provided with the valve seat; the front section of the valve core is fixed with the valve core front section sealing material; the rear section of the valve core is fixedly connected with the bottom of the elastic member mounting seat; when the push rod directly moves downward under the driving action of the driving mechanism, the integral formed by the elastic member mounting seat, the push rod pressing block and the elastic member moves downward; when the elastic member mounting seat moves downward, the valve core is pushed to move to a position close to the valve seat; when the valve core front section sealing material of the valve core contacts with the valve seat, the passage from the liquid inlet to the liquid outlet is cut off, and the valve is closed.

[0012] Preferably, the liquid inlet and the liquid outlet of the valve body are respectively designed with a clamping sleeve connected with a pipeline.

[0013] Preferably, the rear section of the valve core is fixedly connected with the bottom of the elastic member mounting seat through an elastic pin shaft.

[0014] Preferably, the contact surface between the valve seat and the valve core adopts a bellows seal; the middle section of the valve core is welded and sealed with the bellows.

[0015] Preferably, the valve seat and the bellows are sealed by a sealing gasket.

[0016] Preferably, the valve rod and the valve body are connected and fixed by a pressing nut.

[0017] Preferably, the driving mechanism comprises a motor, an encoder, a speed reducer, a ball screw, a sliding block, a linear guide rail, a lower proximity switch and an upper proximity switch.

[0018] The output end of the motor is connected with the ball screw through the speed reducer, the ball screw is equipped with the sliding block, the motor drives the rotating movement of the ball screw, and then the rotating movement is converted into the linear movement of the sliding block; the linear guide rail is arranged on the sliding direction of the sliding block, so that the sliding block moves along the linear guide rail; the encoder is used for measuring the rotating angle of the motor, and then the rotating angle can be converted into the displacement of the sliding block;

[0019] The upper proximity switch and the lower proximity switch are arranged at the upper limit position and the lower limit position of the sliding block respectively.

[0020] Preferably, the driving mechanism further comprises a shaft sleeve, a bearing, a bearing support and a limiting block.

[0021] The ball screw is connected with the speed reducer through the shaft sleeve; the ball screw is arranged on the bearing, the bearing is fixed in the inner part of the shell through the bearing support, and the bearing reduces the lateral disturbance of the ball screw; the limiting block is arranged on the side surface of the sliding block.

[0022] The application further provides a regulating method of the low-temperature electric regulating valve based on the adjustable pre-tightening force.

[0023] Step 1, in the initial state, the valve core is located at the fully open position point, at this time, the elastic member is in the compressed state through the limiting of the elastic member mounting seat and the push rod, and the pre-tightening pressure of the elastic member is F0.

[0024] Step 2, the first stage of valve closing: when the valve needs to be closed, the motor is started, the motor starts to rotate, and the encoder records the rotating angle of the motor in real time; the motor reduces the rotating speed by a certain proportion through the speed reducer to improve the torque, and then drives the rotating movement of the ball screw; the rotating movement of the ball screw is converted into the linear movement of the sliding block; when the sliding block moves linearly downward, the push rod moves linearly downward, thereby driving the downward movement of the whole formed by the elastic member mounting seat, the push rod pressing block and the elastic member; when the elastic member mounting seat moves downward, the valve core moves to the position close to the valve seat; when the valve core moves to the closing position point, the valve core front section sealing material of the valve core just contacts the valve seat, so as to cut off the passage from the liquid inlet to the liquid outlet, and the valve is closed; at this time, the elastic member is in the same initial compressed state, the sealing force between the valve seat and the valve core sealing surface is 0; in the first stage, the data recorded by the encoder is converted into the linear movement distance of the valve core, and the movement distance of the valve core in the first stage is equal to the movement distance of the push rod in the first stage, and the movement distance of the push rod in the first stage is recorded as L1.

[0025] Step 3, the second stage of valve closing: the position of the elastic element mounting seat and the valve core remains unchanged, the push rod continues to generate a pushing force under the driving action of the motor, at this time, the valve core front section sealing material of the valve core begins to deform, and a counterforce is generated, until the pushing force of the push rod is greater than the pre-tightening pressure of the elastic element, the elastic element begins to deform, and the deformation amount of the elastic element in the second stage is equal to the movement distance of the push rod in the second stage; and the movement distance of the push rod in the second stage is the total movement distance of the push rod detected by the encoder minus L1;

[0026] Since the sealing force between the valve seat and the valve core sealing surface is equal to the pre-tightening pressure of the elastic element plus the elastic force generated by the deformation of the elastic element in the second stage, the sealing force between the valve seat and the valve core sealing surface can be detected; when the sealing force between the valve seat and the valve core sealing surface reaches the requirement, the motor stops rotating, and at this time, the valve is in a closed state;

[0027] Step 4, when the valve is to be opened, the motor is started, the motor begins to rotate in the reverse direction, and the encoder records the rotation angle of the motor in real time; the motor reduces the rotation speed by a certain proportion through the speed reducer to improve the torque, and then drives the ball screw to rotate; the rotation of the ball screw is converted into the linear motion of the sliding block; when the sliding block moves linearly upward, the push rod is pulled to move linearly upward, and the elastic element and the valve core front section sealing material begin to recover the deformation; when the elastic element recovers to the initial state, the push rod drives the whole formed by the elastic element mounting seat, the push rod pressing block and the elastic element to move linearly upward; when the elastic element mounting seat moves upward, it directly pulls the valve core away from the valve seat until the valve core moves to the completely open position point, and the motor stops rotating, at this time, the valve is in a completely open state.

[0028] The low-temperature electrically adjusted valve with adjustable pre-tightening force and the adjusting method provided by the application have the following advantages:

[0029] (1) In the valve closing process, the sealing force between the valve core and the valve seat can be simply, quickly and accurately detected, so that the sealing force between the valve core and the valve seat is controlled in the required range, the pre-tightening force of the adjusting valve is changed from non-adjustable to adjustable, the pre-tightening force adjustment of the close fit of the valve seat and the valve core sealing surface is more reasonable, the pre-tightening force is prevented from being too large or too small, the valve core wear is effectively reduced under the premise of meeting the leakage requirement, and the service life of the valve is improved;

[0030] (2) In the valve closing process, since the elastic element has an initial pre-tightening force, the speed at which the sealing force between the valve core and the valve seat reaches the required value can be accelerated, and the valve closing speed is accelerated;

[0031] (3) The initial pre-tightening force of the elastic element is adjustable, and the use is flexible and convenient.

[0032] (4) By arranging the bellows sealing structure, the low-temperature medium cold quantity is effectively isolated from the electrical executing element in the upper half part, and the application is suitable for low-temperature use.

[0033] (5) Design structure is advanced and reasonable, effectively reduces the size of the whole valve. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The overall cross-sectional structure schematic diagram of the low-temperature electric regulating valve with adjustable pre-tightening force provided by the application is shown in the figure;

[0035] Figure 2 The local cross-sectional structure schematic diagram of the low-temperature electric regulating valve with adjustable pre-tightening force provided by the application is shown in the figure;

[0036] Wherein:

[0037] 1: encoder; 2: motor; 3: speed reducer; 4: shaft sleeve; 5: bearing; 6: bearing support; 7: ball screw; 8: limit block; 9: lower proximity switch; 10: push rod; 11: sliding block; 12: push rod joint; 13: baffle; 14: cover; 15: push rod pressing block; 16: elastic piece mounting seat; 17: valve stem; 18: valve core; 19: elastic piece; 20: elastic pin shaft; 21: corrugated pipe; 22: compression nut; 23: sealing gasket; 24: valve core front section sealing material; 25: valve seat; 26: valve body; 27: clamping sleeve. 28: linear guide rail; 29: upper proximity switch; 30: liquid inlet; 31: liquid outlet. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects of the application clearer, the application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application.

[0039] In the description of the application, it should be noted that the terms "front", "back", "upper" and "lower" are determined based on the specific use habits of the small-flow liquid nitrogen low-temperature regulating valve, and are only for the convenience of describing the application and simplifying the description, and are not indicative or implied that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the application.

[0040] The application provides a low-temperature electric regulating valve with adjustable pre-tightening force and a regulating method, which is small in volume and structure, suitable for low-temperature medium, can ensure the accurate realization of sealing pre-tightening force when the valve is closed, prevent excessive pre-tightening force and insufficient pre-tightening force, effectively reduce the wear of the valve core under the premise of meeting the leakage requirement, and improve the service life of the valve.

[0041] REFERENCE Figure 1 The low-temperature electric regulating valve with adjustable pre-tightening force comprises a valve body structure, a pre-tightening force adjusting structure and a driving mechanism. The valve body structure, the pre-tightening force adjusting structure and the driving mechanism will be introduced in detail as follows:

[0042] Pre-tightening force adjusting structure

[0043] The pre-tightening force adjusting structure comprises an elastic member mounting seat 16, an elastic member 19, a push rod pressing block 15, a push rod 10, a cover 14 and a baffle 13.

[0044] The bottom of the cover 14 is provided with a threaded opening; the top end of the valve rod 17 is sealingly and fixedly connected with the threaded opening of the cover 14; the bottom end of the valve rod 17 is sealingly and fixedly connected with the opening of the valve body 26; the baffle 13 is fixedly installed above the threaded opening of the cover 14; the baffle 13 and the inner chamber of the valve rod 17 form a movement chamber; the top end of the push rod 10 is located inside the cover 14 and is connected with a driving mechanism; when the driving mechanism is a screw rod and a sliding block, the push rod is screw-connected with the sliding block through a push rod joint 12, so that the assembly is convenient, the strength is reliable and the service life is long. The bottom end of the push rod 10 extends into the movement chamber through the baffle 13; the bottom end of the push rod 10 has a stepped protrusion; the inside of the elastic member mounting seat 16 has a chamber for placing the elastic member 19, wherein the elastic member can be a spring, can be pre-compressed according to requirements, the pre-compression force can be set, generally a pre-tightening force matched with a sealing material is selected and a certain allowance is left. The elastic member 19 is in surface contact with the push rod 10, and in the closing process, the elastic member does not deform before the push force reaches the pre-compression force of the elastic member. The top of the elastic member mounting seat 16 is screw-connected with the push rod pressing block 15 to form an integral movement component; and the integral movement component is provided with a stepped groove matched with the stepped protrusion; the integral movement component is hung on the stepped protrusion of the push rod 10 through the stepped groove, at this time, the elastic member 19 located inside the elastic member mounting seat 16 is located directly below the push rod 10, the elastic member 19 is initially in a compressed state and has a pre-tightening force.

[0045] Valve body structure

[0046] The valve body structure comprises a valve body 26, a valve seat 25, a liquid inlet 30, a liquid outlet 31, a valve rod 17 and a valve core 18.

[0047] The valve body 26 is arranged below the valve rod 17 and is fixedly connected with the valve rod 17 through a compression nut 22; the valve body 26 is provided with the liquid inlet 30 and the liquid outlet 31; the liquid inlet 30 and the liquid outlet 31 of the valve body 26 are respectively designed with a clamping sleeve 27 connected with a pipeline.

[0048] The valve body 26 has a valve seat 25 in the interior; the front section of the valve core 18 is fixed with a valve core front section sealing material 24, which is made of low-temperature-resistant material, such as PTFE, PCTFE, etc. The rear section of the valve core 18 is fixedly connected with the bottom of the elastic element mounting seat 16; in actual application, the rear section of the valve core 18 is fixedly connected with the bottom of the elastic element mounting seat 16 through the elastic pin shaft 20. When the push rod 10 directly moves downward under the driving action of the driving mechanism, the whole formed by the elastic element mounting seat 16, the push rod pressing block 15 and the elastic element 19 moves downward; when the elastic element mounting seat 16 moves downward, the valve core 18 is pushed to move to a position close to the valve seat 25; when the valve core front section sealing material 24 of the valve core 18 contacts with the valve seat 25, the passage from the liquid inlet 30 to the liquid outlet 31 is cut off, and the valve is closed.

[0049] In the present application, the contact surface between the valve seat 25 and the valve core 18 is sealed by the bellows 21, which has the advantages of effectively isolating the low-temperature medium from the heat exchange with the external structure, and generally can adopt the form of welded bellows to ensure the use effect of the low-temperature medium. The middle section of the valve core 18 is welded and sealed with the bellows 21. The valve seat 25 and the bellows 21 are sealed by the sealing gasket 23, which can be made of silver-plated 316 stainless steel gasket.

[0050] Driving mechanism

[0051] The driving mechanism is used for driving the push rod 10 to move linearly up and down.

[0052] The driving mechanism comprises a motor 2, an encoder 1, a speed reducer 3, a ball screw 7, a sliding block 11, a linear guide rail 28, a lower proximity switch 9 and an upper proximity switch 29.

[0053] The output end of the motor 2 is connected with the ball screw 7 through the speed reducer 3; the ball screw and the motor are provided with a speed reducer, and a micro gear box is selected to generate high torque at low speed of the motor; the motor-speed reducer combination brings higher efficiency, and is an economic solution.

[0054] The ball screw 7 is provided with the sliding block 11, the motor 2 drives the ball screw 7 to rotate, and then the linear motion of the sliding block 11 is converted; the linear guide rail 28 is installed in the sliding direction of the sliding block 11, so that the sliding block 11 moves along the linear guide rail 28; the encoder 1 is used for measuring the rotation angle of the motor 2, and then the displacement of the sliding block 11 is converted; the encoder has compact structure, high resolution and high dynamic performance.

[0055] In the upper and lower limit position of the slider 11, the upper proximity switch 29 and the lower proximity switch 9 are installed respectively. The proximity switch is arranged to effectively prevent the valve core and the corrugated pipe from being damaged when the valve is opened or closed and the encoder fails to work.

[0056] The driving mechanism further comprises a shaft sleeve 4, a bearing 5, a bearing support 6 and a limiting block 8; the ball screw 7 is connected with the speed reducer 3 through the shaft sleeve 4; the ball screw 7 is installed on the bearing 5, and the bearing 5 is fixed to the inside of the cover 14 through the bearing support 6; the bearing 5 reduces the lateral disturbance of the ball screw 7 and realizes accurate displacement control. The limiting block 8 is arranged on the side surface of the slider 11.

[0057] In order to ensure the reliability of the execution components in a low-temperature and humid environment, the shaft sleeve 4, the bearing 5, the bearing support 6, the ball screw 7, the limiting block 8, the lower proximity switch 9, the push rod 10 and the linear guide rail 28 are externally provided with the protective cover 14, which has the effects of waterproofing and dustproofing.

[0058] The application further provides a regulating method of the low-temperature electric regulating valve based on the adjustable pre-tightening force.

[0059] Step 1: In general, the stroke of the valve opening or closing is 3-5 mm. In the initial state, the valve core 18 is located at the fully open position point, at this time, the elastic member 19 is in a compressed state through the limiting of the elastic member mounting seat 16 and the push rod 10, and the pre-tightening pressure of the elastic member 19 is F0.

[0060] Step 2: First stage of valve closing: when the valve needs to be closed, the motor 2 is started, the motor 2 starts to rotate, and the encoder 1 records the rotation angle of the motor 2 in real time; the motor 2 reduces the rotation speed by a certain proportion through the speed reducer 3 to improve the torque, thereby driving the ball screw 7 to rotate; the rotation of the ball screw 7 is converted into the linear motion of the slider 11; when the slider 11 moves linearly downward, the push rod 10 is pushed to move linearly downward, thereby driving the whole formed by the elastic member mounting seat 16, the push rod pressing block 15 and the elastic member 19 suspended on the push rod 10 to move downward; when the elastic member mounting seat 16 moves downward, the valve core 18 is pushed to move to the position close to the valve seat 25; when the valve core 18 moves to the closing position point, the valve core front section sealing material 24 of the valve core 18 just contacts the valve seat 25, thereby cutting off the passage from the liquid inlet 30 to the liquid outlet 31, and the valve is closed; at this time, the elastic member 19 is the same as the initial compression state and does not further deform; the sealing force between the valve seat and the valve core sealing surface is 0; in the first stage, the data is recorded by the encoder 1 and is converted into the linear motion distance of the valve core 18, and the motion distance of the valve core 18 in the first stage is equal to the motion distance of the push rod 10 in the first stage, and the motion distance of the push rod 10 in the first stage is recorded as L1.

[0061] Step 3, the second stage of valve closing: the position of the elastic element mounting seat 16 and the valve core 18 remains unchanged, the push rod 10 continues to generate a pushing force under the driving action of the motor 2, at this time, the valve core front section sealing material 24 of the valve core 18 begins to deform, generating a counteracting force, until the pushing force of the push rod 10 is greater than the pre-tightening pressure of the elastic element 19, the elastic element 19 begins to deform, and the deformation amount of the elastic element 19 in the second stage is equal to the movement distance of the push rod 10 in the second stage; and the movement distance of the push rod 10 in the second stage is the total movement distance of the push rod detected by the encoder minus L1;

[0062] Since the sealing force between the valve seat and the valve core sealing surface is equal to the pre-tightening pressure of the elastic element 19 plus the elastic force generated by the deformation of the elastic element 19 in the second stage, the sealing force between the valve seat and the valve core sealing surface can be detected; when the sealing force between the valve seat and the valve core sealing surface reaches the requirement, the motor 2 stops rotating, at this time, the valve is in a closed state;

[0063] In the present application, the elastic element and the push rod are in surface contact, and the elastic element does not deform before the pushing force reaches the pre-tightening pressure of the elastic element. Only when the pushing force reaches the pre-tightening pressure of the elastic element, the elastic element deforms.

[0064] Step 4, when the valve is to be opened, the motor 2 is started, the motor 2 begins to rotate in reverse, and the encoder 1 records the rotation angle of the motor 2 in real time; the motor 2 reduces the rotation speed by a certain proportion through the speed reducer 3 to increase the torque, thereby driving the ball screw 7 to rotate; the rotation of the ball screw 7 is converted into the linear motion of the sliding block 11; when the sliding block 11 moves linearly upward, the push rod 10 is pulled to move linearly upward, and the elastic element 19 and the valve core front section sealing material 24 begin to recover deformation; when the elastic element 19 recovers to the initial state, the push rod 10 drives the entire body formed by the elastic element mounting seat 16, the push rod pressing block 15 and the elastic element 19 to move linearly upward; when the elastic element mounting seat 16 moves upward, it directly pulls the valve core 18 away from the valve seat 25, until the valve core 18 moves to the fully open position point, the motor 2 stops rotating, at this time, the valve is in a fully open state.

[0065] The low-temperature electrically adjustable valve with adjustable pre-tightening force and the adjusting method provided by the present application have the following advantages:

[0066] (1) In the process of closing the valve, the sealing force between the valve core and the valve seat can be simply, quickly and accurately detected, so that the sealing force between the valve core and the valve seat is controlled within the required range, the pre-tightening force of the adjustable valve is changed from non-adjustable to adjustable, the pre-tightening force adjustment of the close fit of the valve seat and the valve core sealing surface is more reasonable, the pre-tightening force is prevented from being too large or too small, the valve core wear is effectively reduced under the premise of meeting the leakage requirement, and the service life of the valve is improved;

[0067] (2) In the valve closing process, because the elastic member has initial pre-tightening force, the sealing force between the valve core and the valve seat can be accelerated to reach the required value, and the valve closing speed is accelerated;

[0068] (3) The initial pre-tightening force of the elastic member is adjustable, and the use is flexible and convenient.

[0069] (4) By setting the bellows sealing structure, the low-temperature medium cold conduction to the upper half of the electrical executing element is effectively isolated, and it is suitable for low-temperature use;

[0070] (5) The design structure is advanced and reasonable, and the overall size of the valve is effectively reduced.

[0071] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A cryogenic motor-operated regulating valve with adjustable pre-tension, characterized in that The pre-tightening force adjusting structure comprises a push rod (10) and an integral moving component, the bottom end of the push rod (10) has a stepped protrusion, the integral moving component is provided with a stepped groove matched with the stepped protrusion, the integral moving component is hung on the stepped protrusion of the push rod (10) through the stepped groove, and the integral moving component comprises an elastic element mounting seat (16); and The valve body structure comprises a valve body (26), a valve core (18) and a valve seat (25) arranged inside the valve body (26), the front section of the valve core (18) is fixed with a valve core front section sealing material (24), and the rear section of the valve core (18) is fixedly connected with the bottom of the elastic element mounting seat (16); When the integral moving component is driven by the push rod (10) to move downward or upward, the valve core (18) is driven to move to different positions to change the sealing force between the valve core front section sealing material (24) and the valve seat (25), so that the valve is switched between an initial state, a first stage of valve closing, a second stage of valve closing and a completely open state of the valve; The integral moving component further comprises an elastic element (19) arranged in the elastic element mounting seat (16), and the elastic element (19) is located directly below the push rod (10); In the initial state, the elastic element (19) is in a compressed state through the limiting of the elastic element mounting seat (16) and the push rod (10), and the pre-tightening pressure of the elastic element (19) is F0; In the first stage of valve closing, the movement distance of the push rod (10) is L1, the movement distance of the valve core (18) is equal to the movement distance L1 of the push rod (10); neither the elastic element (19) nor the valve core front section sealing material (24) is deformed, and the sealing force between the valve core sealing surface of the valve core front section sealing material (24) and the valve seat (25) is 0; In the second stage of valve closing, the push rod (10) moves to the position where the elastic element (19) is deformed and the valve core front section sealing material (24) is deformed until the sealing force between the valve core sealing surface of the valve core front section sealing material (24) and the valve seat (25) reaches the requirement, and the push rod (10) stops moving. The pre-tightening force adjusting structure further comprises a baffle (13), the valve body structure comprises a valve rod (17), and the bottom end of the valve rod (17) is sealingly and fixedly connected with the opening of the valve body (26) through a compression nut (22); 2. Cryogenic motor-operated regulating valve with adjustable pre-tension according to claim 1, characterized in that The baffle (13) and the inner cavity of the valve rod (17) form a movement cavity, the bottom end of the push rod (10) extends into the movement cavity through the baffle (13), and the integral moving component is located in the movement cavity; In the first stage of valve closing, the push rod (10) drives the integral moving component to move downward in the movement cavity, so that the valve core (18) moves to a closed position. ​ In the second stage of valve closing, the position of the integral moving part in the moving chamber is unchanged when the push rod (10) moves, so that the elastic member (19) is deformed and the valve core front sealing material (24) is deformed.

3. Cryogenic motor-operated regulating valve with adjustable pre-tension according to claim 2, characterized in that The sealing force between the valve core sealing surface of the valve core front sealing material (24) and the valve seat (25) is equal to the pre-tightening pressure of the elastic member (19) plus the elastic force generated by the deformation of the elastic member (19) in the second stage of valve closing; The elastic force generated by the deformation of the elastic member (19) in the second stage of valve closing is obtained by the deformation amount of the elastic member (19) in the second stage of valve closing; The deformation amount of the elastic member (19) in the second stage of valve closing is equal to the total movement distance of the push rod (10) minus the movement distance of the push rod (10) in the first stage of valve closing.

4. Cryogenic motor-operated regulating valve with adjustable pre-tension according to claim 1, characterized in that The elastic member (19) and the push rod (10) form a surface contact, so that the elastic member (19) is deformed only when the pushing force of the push rod (10) on the elastic member (19) reaches the pre-tightening pressure of the elastic member (19).

5. The cryogenic motor-operated regulating valve of claim 1, wherein The integral moving part further comprises a push rod pressing block (15), the top of the elastic member mounting seat (16) is threadedly connected with the push rod pressing block (15), and the stepped groove is defined by the push rod pressing block (15) and the elastic member mounting seat (16) together.

6. Cryogenic motor-operated regulating valve with adjustable pre-tension according to claim 2, characterized in that Further comprising a driving mechanism for driving the push rod (10) to move linearly up and down, the driving mechanism comprising an encoder (1), a motor (2), a speed reducer (3), a ball screw (7) and a sliding block (11) assembled on the ball screw (7); The output end of the motor (2) is connected with the ball screw (7) through the speed reducer (3), and the sliding block (11) is connected with the push rod (10); the encoder (1) measures the rotation angle of the motor (2), which is further converted into the movement distance of the push rod (10).

7. Cryogenic motor-operated regulating valve with adjustable pre-tension according to claim 6, characterized in that The driving mechanism further comprises a linear guide rail (28) in the sliding direction of the sliding block (11), so that the sliding block (11) moves along the linear guide rail (28); An upper proximity switch (29) and a lower proximity switch (9) are respectively installed at the upper and lower limit positions of the sliding block (11).

8. Cryogenic motor-operated regulating valve with adjustable pre-tension according to claim 6, characterized in that The pre-tightening force adjusting structure further comprises a cover shell (14), the speed reducer (3) and the valve body structure are respectively arranged on the upper and lower sides of the cover shell (14), the baffle (13) is fixedly installed on the threaded opening of the cover shell (14), and the top end of the push rod (10) penetrates through the baffle (13) and is located in the interior of the cover shell (14); The top end of the valve rod (17) is sealingly and fixedly connected with the threaded opening of the cover shell (14).

9. Cryogenic motor-operated regulating valve with adjustable pre-tension according to claim 8, characterized in that The driving mechanism further comprises a shaft sleeve (4), a bearing (5), a bearing support (6) and a limiting block (8) arranged on the side of the sliding block (11); The ball screw (7) is installed on the bearing (5) and connected with the speed reducer (3) through the shaft sleeve (4); The bearing (5) is fixed inside the housing (14) through the bearing support (6) to reduce lateral disturbance of the ball screw (7).

10. Cryogenic motor-operated regulating valve with adjustable pre-tension according to claim 1, characterized in that The valve body (26) has an inlet (30) and an outlet (31), when the front sealing material (24) of the valve core contacts the valve seat (25), the passage from the inlet (30) to the outlet (31) is cut off, and the valve is closed. The inlet (30) and the outlet (31) are respectively designed with a clamping sleeve (27) connected with a pipeline.

11. Cryogenic motor-operated regulating valve with adjustable pre-tension according to claim 1, characterized in that The rear section of the valve core (18) is fixedly connected with the bottom of the elastic element mounting seat (16) through an elastic pin shaft (20).

12. The cryogenic motor-operated regulating valve of claim 1, wherein, The contact surface between the valve seat (25) and the valve core (18) is sealed by a bellows (21), the middle section of the valve core (18) is welded and sealed with the bellows (21), and the valve seat (25) and the bellows (21) are sealed by a sealing gasket (23).

13. A method of regulating a cryogenic motor-operated regulating valve according to any one of claims 1-12, characterized in that, The method comprises the following steps: The first stage of valve closing: the push rod (10) moves downward and pushes the whole moving part to move downward to drive the valve core (18) to move downward, so that the front sealing material (24) of the valve core just contacts the valve seat (25); The second stage of valve closing: the push rod (10) continues to move downward and applies a pushing force to the elastic element (19), the position of the elastic element mounting seat (16) and the valve core (18) remains unchanged, so that the elastic element (19) deforms and the front sealing material (24) of the valve core deforms, when the sealing force between the valve core sealing surface of the front sealing material (24) of the valve core and the valve seat (25) reaches the requirement, the push rod (10) stops moving, and at this time the valve is in a closed state; The stage of opening the valve: the push rod (10) moves upward, the elastic element (19) and the front sealing material (24) of the valve core recover elastic deformation, when the elastic element (19) recovers to the initial state, the push rod (10) drives the whole moving part to move upward to pull the valve core (18) away from the valve seat (25), until the valve core (18) moves to a completely open position point, the push rod (10) stops moving, and at this time the valve is in a completely open state.

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