1101 results about "Fluid control" patented technology

The invention discloses a method and system for controlling the opening degree of a pipeline flow automatic adjusting valve, and relates to the technical field of automatic control. The method comprises the steps that real-time flow data in a pipeline and real-time pressure difference data of upstream and downstream of a valve are obtained; comparing the real-time flow data with a preset target flow to obtain a flow deviation, and generating a feedforward compensation signal by a proportional-integral-differential controller according to the flow deviation and the real-time pressure difference data; the flow deviation is input into a PID controller, and a proportional-integral-differential controller generates a feedback control signal; generating a composite control signal according to a superposition result of the feed-forward compensation signal and the feedback control signal; and the electric actuating mechanism is driven to adjust the opening degree of the valve according to the compound control signal, the actual opening degree of the valve is obtained through the position sensor, and the actual opening degree is fed back to the proportional-integral-differential controller. The invention provides a brand new solution with high robustness, high precision and low maintenance cost for industrial fluid control.

The invention relates to the technical field of fluid control, and discloses a split type mass flow controller calibration method, system and equipment. According to the method, a control unit, a valve unit, a detection unit and a fluid passage unit are connected through detachable interfaces through a split type modular design, and the problem that a traditional integrated structure is difficult to calibrate and maintain is solved. A flow mapping relation model is established by adopting temperature difference and pressure data, and dynamic correction is performed in combination with an environment temperature compensation coefficient, so that the detection precision is remarkably improved. Through cooperative control of a flow closed loop and a valve element displacement closed loop, precise adjustment of the opening degree of the valve is achieved, and the stability and the dynamic response performance of flow control are effectively improved. The system has the advantages of being flexible in structure, high in calibration precision and high in environmental adaptability, and is suitable for the high-precision flow control field of semiconductors, biological medicine and the like.

The invention discloses a display screen defect detection system and a use method thereof. The use method comprises the following steps: S1, controlling a workpiece fixing module to adsorb and fix a display screen placed on a working platform; s2, acquiring edge curvature data of the display screen through a curvature identification module, and sending the edge curvature data to a central control module; s3, the central control module generates a first control instruction based on the received curvature data, the central control module drives the fluid control unit to precisely regulate and control the gas supply amount of each gas bag according to the edge data obtained by the curvature recognition module through the flexible supporting structure formed by connecting the rotatable subunits in series and the pneumatically-driven deformation driving part, and the gas supply amount of each gas bag is adjusted and controlled. And the bending radian of the self-adaptive detection module is dynamically matched with the curvature of the display screen. Metal wires and reinforcing wires in the air bag cooperatively provide structural support and cooperate with magnetic sheets to adsorb a magnetic field to stabilize the rotation angle, and it is ensured that the lighting unit and the image acquisition assembly strictly follow the curved surface profile.

The invention provides an online monitoring device for multiple nuclides in liquid effluent, and particularly relates to the technical field of radioactive substance detection. The online monitoring device comprises a shell, a cascade separation module, a fluid control module, a detection module and a control system, the cascade separation module, the detection module and the control system are arranged in the shell, the cascade separation module comprises a plurality of resin columns and a plurality of separated liquid collecting bottles communicated with the resin columns, and the separated liquid collecting bottles are communicated with the resin columns. The fluid control module comprises a liquid storage device, an injection pump and a control valve, the liquid storage device is respectively communicated with the plurality of resin columns through pipelines, the injection pump and the control valve are respectively arranged on the pipelines and are used for controlling the flow direction and the flow velocity of fluid in the liquid storage device, and the detection module is used for detecting the radioactive activity of nuclide; the control system is used for controlling operation of the cascade separation module, the fluid control module and the detection module. According to the invention, synchronous monitoring of multiple nuclides is realized, the multi-nuclide monitoring efficiency is improved, and the monitoring cost is reduced.

The invention relates to the technical field of fluid control equipment, and discloses an anti-backflow valve which comprises a valve body, a valve rod, a sealing valve seat and a valve plate, an output pipe is arranged on the outer wall of the right side of the valve body, an input pipe is arranged at the bottom of the valve body, the sealing valve seat is fixedly installed in the input pipe, and the valve plate is pressed on the sealing valve seat. The valve rod is rotated to drive the connecting disc to rise, the spring drags the valve plate to rise, the valve plate is separated from the sealing valve seat, the inserting rod is arranged, on one hand, the valve plate is guided, on the other hand, when the valve needs to be closed, the valve rod can drive the inserting rod to move downwards, and then the valve plate is tightly pressed on the sealing valve seat; if the water pressure in the input pipe is lower than the water pressure in the valve cavity of the valve body, the pressure acting on the upper surface of the valve plate can downwards press the valve plate at the moment, then the valve plate is pressed on the sealing valve seat, the valve is closed, and then the backflow problem is avoided.

The invention discloses a flexible riser vibration response characteristic analysis method, and relates to the technical field of ocean engineering. According to the method, a flexible riser vibration model is established based on a vibration theoretical model and a fluid control equation for vibration analysis, a theoretical time domain response curve of the flexible riser is obtained through MATLAB calculation, and then a flexible riser three-dimensional simulation model is established in an ANSYS Workbench integrated simulation platform. According to the method, a flexible riser three-dimensional simulation model is constructed, material constitutive parameters, boundary conditions and load application of the flexible riser three-dimensional simulation model are configured, then simulation is performed in an ANSYS Workbench integrated simulation platform by using the flexible riser three-dimensional simulation model, bidirectional fluid-solid coupling analysis is performed by coupling a Fluent flow field system and a Transient Stratum module, the radial displacement time history of the flexible riser under a preset working condition is obtained, and the radial displacement time history of the flexible riser under the preset working condition is calculated. And extracting resonance characteristics of the flexible riser. According to the method, the vibration response characteristics of the deep-sea flexible riser under the influence of internal and external fluids in the service process are accurately obtained, and a foundation is laid for guiding the structural stability of a deep-sea operation system.

The invention discloses a quick-change type ball valve with double mechanical interlocking assemblies, and particularly relates to the technical field of fluid control equipment, the quick-change type ball valve comprises a first ball valve and a second ball valve, and the second ball valve is installed on the side face of the first ball valve through a buckle; the first ball valve comprises a first valve element, a first valve seat, a first ball valve handle, a marble, a first pin and a first connecting buckle, a circular hole is formed in the upper wall of the first valve seat, a horizontally-placed first rectangular fillet long plate is arranged above the first ball valve handle, and a second arc-shaped groove is formed in the fillet position; a vertically-placed first threaded long rod structure is installed below the first rectangular fillet long plate, the first threaded long rod structure of the first ball valve handle vertically penetrates through a first circular hole of the first valve seat, and the first threaded long rod structure is rotationally connected with the first circular hole of the first valve seat.

The invention relates to the technical field of fluid control, and discloses a drip-proof self-adaptive fluid dispensing control method and system. The method comprises the following steps: acquiring an image sequence, pressure data and viscosity change data when fluid is disconnected; positioning an abnormal disconnection moment, extracting a corresponding picture, and extracting a necking diameter and a necking length from the picture; calculating the real-time change rate of the necking diameter based on the necking parameters, obtaining the state identification that the fluid is about to be disconnected, and predicting the disconnection opportunity; integrating the cut-off opportunity predicted value and the viscosity data to obtain a comprehensive data set, and calibrating core parameters to generate an adaptive signal waveform; acquiring a real-time flow velocity data correction waveform, and generating an optimization control signal; and extracting a key intervention point, applying pulse intervention, calculating the colloid residual quantity, performing iterative optimization if the colloid residual quantity exceeds a preset threshold value, and performing no intervention if the colloid residual quantity does not exceed the preset threshold value, thereby finally obtaining a non-leakage control sequence. According to the method, the necking characteristic of the fluid can be accurately captured, the working condition is dynamically adapted, non-dripping dispensing is realized, and the control precision and stability are improved.

The invention discloses a flip flow energy dissipation scouring numerical simulation method and device and a storage medium, and relates to the technical field of water conservancy projects. The method comprises the steps that a multiphase fluid model and physical parameters are set in a CFD solver, and a fluid control equation is solved; a particle set is generated in the DEM solver, and physical and mechanical parameters and interaction parameters of particles are set; the CFD solver calculates the acting force of the fluid on the particles based on the flow field information and transmits the acting force to the DEM solver; the DEM solver solves a particle motion equation according to the acting force, the motion state of the particles is updated, and the updated motion state of the particles is transmitted back to the CFD solver; the CFD solver solves the fluid control equation again according to the particle motion state, and the flow field information is updated. According to the method, the interaction process between the fluid and the particles is considered, information interaction between fluid distribution and particle movement is achieved, and the simulation precision of the hydraulic scouring process is improved.

The invention relates to the technical field of medical diagnosis, and discloses an integrated nucleic acid detection method and device based on a micro-fluidic chip, the integrated nucleic acid detection device comprises a micro-fluidic chip module, a liquid control module, a temperature control module, an optical detection module and a data processing module, and the multiple modules work cooperatively to realize full-process automatic detection of a sample from splitting decomposition to detection; the micro-fluidic chip module comprises a sample treatment area, a nucleic acid extraction and purification area, a nucleic acid amplification area, a nucleic acid detection area and a waste liquid collection area which are connected through a micro-channel, and a valve is arranged at a key node. Through a fluid control mode combining centrifugal force and air pressure driving and valve combination of non-complex micro-pump micro-valves such as the dissolvable membrane valve, the temperature sensitive valve and the capillary force flow limiting valve, full-flow fluid sequential control can be achieved without integrating a plurality of micro-pump micro-valves; the problems of complex structure, high manufacturing difficulty and high cost caused by integration of multiple micro-pumps and micro-valves of the conventional pressure-driven micro-fluidic chip are solved.

The present invention achieves a larger flow rate of a fluid control valve without increasing a size of an orifice or an actuator. The fluid control valve includes an orifice having a valve seat surface and a valve body having a seating surface to be seated on the valve seat surface. The orifice has a plurality of inflow ports and a plurality of outflow ports that are open along a first direction on the valve seat surface. The plurality of inflow ports and the plurality of outflow ports are arranged side by side in a second direction intersecting the first direction.

To provide a structure for easily arranging a control board in a flow rate ratio control device.SOLUTION: The fluid control device includes a plurality of fluid control devices 2 in which a fluid sensor 22 and a fluid control valve 23 are provided in a flow passage block 21, and a control board 4 for controlling the plurality of fluid control devices 2, and the control board 4 is erected on an upper surface of the flow passage block 21 along an arrangement direction of the plurality of fluid control devices 2.SELECTED DRAWING: Figure 1

The invention relates to the technical field of cone valve multi-mode air supply-energy dissipation cooperative cavitation reduction devices and control methods, and discloses a fluid control device named'cone valve multi-mode air supply-energy dissipation cooperative cavitation reduction devices and control methods'. The conical valve aims to solve the problems that an existing conical valve is serious in cavitation under the working condition of high pressure difference, air supply and energy dissipation functions are separated, and response lags. The device is characterized by comprising three stages of energy dissipation perforated pipes which are arranged at the outlet end of a valve body in a gradient mode, negative pressure injection air supply pipes which are symmetrically arranged outside a flow guide cover and flow guide fins which are welded to the inner wall of a cone, and the three stages of energy dissipation perforated pipes, the negative pressure injection air supply pipes and the flow guide fins cooperate to achieve pressure gradient pressure relief, self-adaptive air supply and flow state stability; the control method dynamically adjusts the air supply intensity based on the opening degree, the pressure difference and the vibration signal. According to the technical scheme, cavitation inception and collapse impact are remarkably restrained, vibration noise is reduced, the service life of the valve is prolonged, an external air source is not needed, the system pressure drop is controllable, and the system is suitable for ultrahigh pressure difference and large-flow hydroelectric working conditions.

The invention belongs to the technical field of fluid control, and particularly relates to a system for predicting nuclear power plant valve opening and flow nonlinear sudden change. The preprocessing and mechanism analysis module is responsible for performing deep processing and consistency review on the data acquired by the sensor, and performing modeling and parameter correction on flow sections of different types of valves in combination with a physical mechanism; the data driving prediction module is responsible for performing XGBoost modeling and reasoning on historical and real-time collected multi-dimensional data on the basis of a physical mechanism analysis result, outputting a fine prediction value of the valve flow and providing a more sensitive response for a nonlinear abrupt change region; and the hybrid model fusion and adaptive updating module is responsible for organically fusing prediction results of the physical mechanism model and the XGBoost model, dynamically adjusting model parameters according to real-time operation data, and realizing high-precision prediction and stable control of the valve flow. According to the invention, real-time and high-precision prediction of non-linear abrupt changes possibly occurring in different opening degree intervals of the valve is realized.

The invention discloses an excrement liquid dynamic proportion regulation and control method based on sensing feedback, and particularly relates to the technical field of waste fluid control, and the method comprises the following steps: arranging a plurality of sensors in an excrement liquid conveying pipeline, collecting multi-parameter data such as flow, conductivity, solid content and the like, calculating a load fluctuation entropy value and a control conflict count value, and calculating a load fluctuation entropy value and a control conflict count value; the current control state is judged, the priority and the execution frequency of proportional integral differential control and self-adaptive control are dynamically adjusted based on the state result, a dilution ratio control signal is generated, a variable frequency pump is driven to be linked with an electric valve, clear water injection and excrement liquid mixing control are achieved, and the solid content is stabilized within the target range; according to the invention, the system state is identified through the combination of entropy and conflict counting, the priority and frequency of the control strategy are dynamically switched, and accurate adjustment under steady state and disturbance is realized; and meanwhile, a dilution ratio control signal is linked with the variable frequency pump and the electric valve, a closed-loop dilution control channel is constructed, and the intelligence and stability of solid content regulation and control are improved.

To improve responsiveness while reducing the effect of noise, a valve control method for controlling a valve of a fluid control device includes generating a target response function converted from the flow rate setting using a target response transfer function; generating a target voltage function by making a correction in nonlinearity of a drive voltage for the valve and a flow rate, with respect to the target response function; generating a feedforward voltage signal from the target voltage function by making a correction corresponding to the delay characteristic of the valve; causing a feedback controller to generate a feedback voltage signal from a deviation between the target response function and a flow rate measurement of a flow rate sensor; generating a corrected command voltage signal using a feedforward voltage signal and the feedback voltage signal; and controlling the valve using the corrected command voltage signal.

The invention relates to the technical field of separation, and discloses a molecular sieve separation system for medical oxygen production, which comprises an adsorption separation group, a fluid control valve group, a pressure monitoring unit and a self-adaptive control center, the self-adaptive control center executes capacity locking logic and regeneration clamping logic based on fluid impedance fingerprint characteristics, monitoring the actual pressurizing duration of the adsorption pressurizing stage in real time, calculating a deviation value between the actual pressurizing duration and the reference adsorption duration, and generating a primary switching instruction; meanwhile, the real-time residual desorption pressure of the other adsorption bed layer is obtained and compared with a regeneration end point pressure threshold value, a final step sequence switching instruction is output when the conditions are met, and self-adaptive locking of the real adsorption capacity of the molecular sieve is achieved by recognizing the adsorption capacity saturation characteristics and decoupling gas source fluctuation.

This invention provides a virtual-real fusion-based force feedback simulation control method for ship rudder control sticks, comprising: constructing a set of fluid control equations for the flow field on the rudder surface; discretizing the set of fluid control equations using a standard structured mesh to obtain a discretized set of fluid control equations; solving the discretized set of fluid control equations based on the finite difference method and boundary conditions to obtain the drag torque value of the fluid acting on the rudder plate; converting the drag torque value into a damping torque value; the control unit outputting a motor drive command based on the magnitude of the damping torque value; and the motor driver, based on the motor drive command output by the control unit, driving the force feedback simulation motor to generate a corresponding simulated damping torque value, which acts on the control stick to produce force feedback. This invention provides real-time control stick force feedback for the helmsman, allowing for direct perception of the ship's navigation status and enhancing steering stability.

The utility model relates to the technical field of fluid control, in particular to an electronic expansion valve. An electronic expansion valve comprises a valve seat, a guide sleeve and a piston assembly, and a valve port is formed in the valve seat; a balance channel is arranged in the electronic expansion valve, one end of the balance channel is located at the end, close to the valve port, of the piston assembly and communicated with the valve port, the other end of the balance channel penetrates through the end, away from the valve port, of the guide sleeve, and a filter screen is arranged at the end, close to the valve port, in the balance channel. The filter screen is arranged in a protruding mode in the direction away from the guide sleeve relative to the piston assembly. According to the filter screen, impurities can be prevented from entering the balance channel to affect normal work of the piston assembly, and when the electronic expansion valve is opened, media can flush media accumulated on the outer side face of the protruding part of the filter screen to prevent the filter screen from being blocked.

The utility model belongs to the technical field of hydraulic valves, and discloses a two-stage buffer overflow valve and a fluid control assembly. The two-stage buffering overflow valve comprises a valve seat assembly, a valve body, a valve element mechanism, an oil passing channel and a buffering piston, the valve seat assembly is provided with an oil inlet, the valve body is arranged at the end, away from the oil inlet, of the valve seat assembly in a sleeving mode, the valve body is provided with an oil outlet, and the valve element mechanism comprises a sliding valve element arranged in the valve seat assembly in a sliding fit mode; the end, away from the oil inlet, of the sliding valve element is provided with a secondary pressure building cavity, the secondary pressure building cavity communicates with the oil inlet, at least part of the oil passing channel is arranged on the sliding valve element and / or the valve seat assembly and / or the valve body, and the oil passing channel communicates with the secondary pressure building cavity and the oil outlet; the buffer piston is arranged on the valve seat assembly in a sliding and sleeving mode and can block or open the oil outlet. By prolonging the completion time of secondary pressure establishment, the buffering effect is improved, and the impact generated when the hydraulic motor is started and braked is reduced.

The invention relates to the field of fluid control devices in semiconductor liquid paths, and provides a precise control on-off valve for a semiconductor liquid path and an assembling method thereof, and the precise control on-off valve comprises a valve seat, a cylinder assembly combined on the valve seat, a diaphragm valve plate accommodated in the valve seat, and an adjusting wheel arranged on an upper cover of the cylinder. The air cylinder assembly comprises an air cylinder upper cover and an air cylinder body which are connected through a rotary lock catch structure, and a piston assembly and a limiting rod set are assembled in the air cylinder assembly. And the diaphragm valve plate is driven by the cylinder assembly to seal or separate from the valve port of the valve seat. The adjusting wheel is connected with the limiting rod set and used for adjusting lifting of the limiting lead screw, and then the maximum upward moving position of the piston assembly and the opening degree of the valve are precisely limited. The valve breaks through the bottleneck that a traditional mechanical valve is prone to abrasion and leakage, achieves the effect of precise fine adjustment of flow, and meanwhile greatly improves the flow stability of long-term operation and the clean safety of an ultra-pure fluid system.

The invention relates to the technical field of ice removal, in particular to an ice removal, ice prevention and spraying integrated device for a cable. Comprising a driving control mechanism, spraying roller brush mechanisms, a guide arm, a hoisting mechanism and a guide way, the guide way is arranged at the lower end of the driving control mechanism, the guide arm is arranged below the guide way, the hoisting mechanism is arranged on the driving control mechanism, and the spraying roller brush mechanisms are connected to a group of opposite side walls of the driving control mechanism. The spraying roller brush mechanism is connected with the driving control mechanism; the driving control mechanism comprises a driving assembly, a fluid control assembly and a main body shell, the fluid control assembly is arranged in the main body shell, the driving assembly is used for controlling the device to move in the extending direction of the cable, one end of the fluid control assembly communicates with the water tank, and the other end is connected with the spraying roller brush mechanism; the fluid control assembly is used for controlling the two spraying roller brush mechanisms to conduct alternate work of sweeping and spraying. And the best coating effect of the anti-icing material is ensured while dirt on the surface of the cable is effectively removed.

The invention relates to the technical field of fluid control, and discloses an ink supply control method, system and device and a storage medium, and the ink supply control method comprises the following steps: obtaining a current ink supply box measurement state and a current actual operation speed of an ink pump; acquiring a historical ink supply box measurement state and a historical ink pump actual operation speed; updating the dynamic model of the ink supply system according to the current and historical data; calculating a feedback control quantity according to the current ink supply box measurement state, a preset ink supply box target state and a preset feedback coefficient; calculating a feedforward control quantity according to the updated dynamic model of the ink supply system and the current and historical data; and calculating an ink pump control signal according to the feedback control quantity and the feedforward control quantity. According to the ink supply control method disclosed by the invention, the dynamic model of the ink supply system is constructed, the control signal of the ink pump is jointly calculated through the feedback control quantity and the feedforward control quantity, the control precision and the anti-interference performance are high, and high-precision stable ink supply is realized.

The invention relates to an electric servo regulating valve and a control method thereof, and belongs to the technical field of fluid control. Comprising a servo motor, a precise planetary reducer, an electric cylinder, a valve frame and an adjusting valve body which are sequentially connected. An absolute encoder is arranged in the servo motor; a ball screw transmission part is integrated in the electric cylinder, the adjusting valve body comprises a valve rod, a valve cover and a valve body, the ball screw transmission part is connected with the precise planetary reducer and the valve rod, and the precise planetary reducer drives the valve rod to do linear motion through a ball screw when rotating, so that the opening degree of the valve is controlled. The servo control driver is used for driving a servo motor and is electrically connected with the main control PLC and the absolute encoder respectively, and the rotation of the servo motor is controlled through the detected motor position and motor speed. The problems that a traditional electric control valve is low in action speed, large in system inertia, low in control precision and the like are solved.

The utility model relates to the technical field of fluid control, in particular to an electronic expansion valve. An electronic expansion valve comprises a valve seat, a guide sleeve and a piston assembly, a valve port is formed in the valve seat, one end of the guide sleeve extends into the valve seat and is connected with the valve seat in a sealed mode, and the guide sleeve is connected with the piston assembly in a sliding mode; the piston assembly comprises a positioning cylinder, a screw rod and a nut seat, one end of the positioning cylinder is arranged in the guide sleeve and is in sliding connection with the guide sleeve, the nut seat is arranged in the positioning cylinder and is connected with the positioning cylinder, one end of the screw rod is arranged in the nut seat in a penetrating mode and is in threaded connection with the nut seat, and the other end of the screw rod is in threaded connection with the nut seat. One end of the guide sleeve extends out of the positioning cylinder, the other end of the guide sleeve extends out of the positioning cylinder, a limiting part is arranged on the guide sleeve, a matching part is arranged on the positioning cylinder, and the limiting part is matched with the matching part to limit circumferential rotation of the positioning cylinder, so that the positioning cylinder can slide along the guide sleeve to adjust the opening degree of the valve port.

The present invention improves the sealability of a fluid control valve, and includes a valve seat having a flat valve seat surface and a valve plug having a flat sitting surface sitting on the valve seat surface. A first surface that is one of the valve seat surface and the sitting surface has a surface hardness higher than a surface hardness of a second surface that is the other one of the valve seat surface and the sitting surface.

The invention discloses an unmanned aerial vehicle self-adaptive landing system and a control method. The system includes a flexible deformable landing gear body, a sensor module, a fluid control module, and a control unit. The undercarriage body contains a flexible chamber filled with a controllable fluid. During landing, the control unit instructs the fluid control module to dynamically adjust the fluid in the chamber based on pressure data monitored by the sensor module, so that the undercarriage main body actively deforms to adapt to an irregular ground profile. Point contact is converted into surface contact, so that landing impact load is effectively dispersed, and stress concentration is avoided; and through an automatic attitude leveling function after landing, the stability and safety of landing of the unmanned aerial vehicle in complex terrains are remarkably improved, and the operation range and autonomy of the unmanned aerial vehicle are expanded.

The invention relates to the technical field of diaphragm valves, and provides a grinding fluid diaphragm valve for semiconductor CMP equipment and an assembling method of the grinding fluid diaphragm valve. The diaphragm valve comprises a valve seat, a wear-resisting diaphragm piece and an adjusting assembly, an inclined annular step face of 3-10 degrees is arranged in the valve seat, the wear-resisting diaphragm piece is provided with a rubber body, a PTFE wear-resisting layer and an embedded threaded piece with a limiting part, and the adjusting assembly comprises an adjusting rod, a diaphragm connecting shaft pressing block, a hand wheel and a movable limiting adjusting nut. Static sealing of non-limit pre-pressing is achieved through slope contact, a runner dead zone is eliminated, and grinding liquid is prevented from crystallizing; the wear resistance is improved through the PTFE wear-resistant layer; the unique design of the limiting adjusting nut allows setting of a closing stroke or reserving of a closing gap, and flexible switching between a full-closing mode and a crystallization leakage prevention mode is achieved. The invention has the characteristics of high cleanliness, long service life and strong process adaptability, and is suitable for semiconductor precision fluid control.

The invention relates to a high-pressure air separation liquid valve with a multi-stage low-temperature self-tightening sealing structure, which relates to the technical field of low-temperature high-pressure fluid control and comprises a valve body assembly, a multi-stage sealing assembly and a valve rod thermal compensation assembly. The multi-stage sealing assembly is arranged on the valve element in a stepped mode and comprises a primary metal hard sealing ring, a secondary modified PTFE sealing ring and a three-stage self-tightening type metal spring energy storage ring, and the main sealing function, the flexible compensation function and the pressure self-tightening function are achieved respectively. The valve rod thermal compensation assembly comprises a titanium alloy valve rod and a copper-nickel alloy thermal buffer sleeve, and the displacement of the sealing face is automatically compensated at the low temperature through the difference between a reserved gap and the thermal expansion coefficient of a material. Through multi-stage sealing cooperation and intelligent thermal compensation, the problem of sealing leakage caused by material failure and thermal deformation under the ultralow-temperature and high-pressure working conditions is effectively solved, all-working-condition reliable sealing is achieved, the safety of the valve in the extreme environment is remarkably improved, and the service life of the valve in the extreme environment is remarkably prolonged.