Totally enclosed microfluidic pressure control system and method

Abstract

This invention provides a fully enclosed microfluidic pressure control system and method, relating to the fields of cryogenic metering and precision pressure control. The system includes a first cryogenic thermostat and a second cryogenic thermostat; a connecting pipe linking the gas phase spaces of the two thermostats to form a fully enclosed gas loop; a gas flow control valve located on the connecting pipe; an active temperature control unit thermally coupled to the second cryogenic thermostat; and a central control system that, based on the deviation between the actual pressure and the target pressure of the first cryogenic thermostat, controls the active temperature control unit to adjust the temperature of the second cryogenic thermostat to generate a pressure difference, and controls the opening of the gas flow control valve according to the deviation, allowing the working gas to transfer within the fully enclosed gas loop to regulate the internal pressure of the first cryogenic thermostat. This invention achieves zero-loss recycling of the working gas and is suitable for high-precision pressure control in applications such as ultra-low temperature physics experiments, quantum computing, and cryogenic thermostats.

Description

Technical Field

[0001] This invention relates to the field of cryogenic metering and precision pressure control technology, and in particular to a fully enclosed microfluidic pressure control system and method. Background Technology

[0002] Cryostats are core equipment that provide a stable ultra-low temperature environment for cutting-edge scientific research such as ultra-low temperature physics experiments, quantum computing, and superconducting electronics. The pressure stability of the working gas inside the cryostat directly affects the accuracy and repeatability of experimental results.

[0003] In existing technologies, pressure control of cryogenic thermostats typically employs an open dynamic gas replenishment system. This system connects high-precision gas flow controllers in series on both the inlet and outlet lines of the thermostat. A proportional-integral-derivative (PID) control algorithm ensures that the inlet flow controller's reading is always slightly greater than the outlet flow controller's reading. This difference is used as the net gas flow entering the thermostat to maintain pressure balance, while excess gas is either directly discharged to the outside of the system or sent to a recovery device. However, this approach has two drawbacks. First, all outflowing working gas is discharged or recovered and cannot be recycled, resulting in significant waste when using expensive rare gases such as helium-3. Second, the pressure control accuracy depends on the absolute accuracy and response consistency of the two flow controllers; drift in either flow meter will lead to control errors, resulting in insufficient long-term stability.

[0004] Therefore, existing solutions suffer from technical problems such as continuous loss of working gas, inability to recycle it, and pressure control accuracy being limited by the absolute accuracy of the flow meter, resulting in poor long-term stability. Summary of the Invention

[0005] This invention provides a fully enclosed microfluidic pressure control system and method to solve the problems of continuous emission of working gas leading to serious waste of expensive gas in existing open dynamic gas replenishment systems, and insufficient long-term stability due to the reliance on the absolute accuracy and response consistency of multiple flow meters for control precision.

[0006] This invention provides a fully enclosed microfluidic pressure control system, comprising: a first cryogenic thermostat and a second cryogenic thermostat; a connecting pipeline connecting the gas phase spaces of the first cryogenic thermostat and the second cryogenic thermostat to form a fully enclosed gas circuit; a gas flow control valve disposed on the connecting pipeline; an active temperature control unit thermally coupled to the second cryogenic thermostat; and a central control system connected to the pressure detection terminal of the first cryogenic thermostat, the gas flow control valve, and the active temperature control unit, respectively. The central control system is used to: control the active temperature control unit to adjust the temperature of the second cryogenic thermostat to generate a pressure difference based on the deviation between the actual pressure and the target pressure of the first cryogenic thermostat; and control the opening of the gas flow control valve according to the deviation, so that the working gas is transferred in the fully enclosed gas circuit to regulate the internal pressure of the first cryogenic thermostat.

[0007] According to the fully enclosed microfluidic pressure control system provided by the present invention, the first cryogenic thermostat and the second cryogenic thermostat have the same structure, volume and material.

[0008] According to the present invention, a fully enclosed microfluidic pressure control system further includes a gas flow meter; the gas flow meter is installed on the connecting pipeline and is connected to the central control system for detecting the gas flow rate in the connecting pipeline.

[0009] According to the present invention, a fully enclosed microfluidic pressure control system further includes a volume regulator; the volume regulator is connected to the gas phase space of the second cryogenic thermostat and is used to regulate the gas pressure in the second cryogenic thermostat by changing the volume.

[0010] According to the present invention, a fully enclosed microfluidic pressure control system is provided, wherein the volume regulator is a bellows volume regulator, and the bellows volume regulator is driven by an external micro-displacement mechanism to achieve volume change.

[0011] According to the present invention, a fully enclosed microfluidic pressure control system is provided, wherein the central control system is also connected to the volume regulator via signal connection; the central control system is used to: control the volume regulator to change the volume of the second low-temperature thermostat to generate a pressure difference based on the deviation between the actual pressure and the target pressure of the first low-temperature thermostat; and control the opening of the gas flow control valve based on the deviation to transfer the working gas in the fully enclosed gas circuit to regulate the internal pressure of the first low-temperature thermostat.

[0012] According to the present invention, a fully enclosed microfluidic pressure control system is provided, wherein the working gas in the fully enclosed gas circuit is helium-3 gas.

[0013] The present invention also provides a fully enclosed microfluidic pressure control method, the method comprising: acquiring the deviation between the actual pressure and the target pressure of a first cryogenic thermostat; controlling an active temperature control unit to adjust the temperature of a second cryogenic thermostat based on the deviation, so that a pressure difference corresponding to the direction of the deviation is generated between the second cryogenic thermostat and the first cryogenic thermostat; controlling the opening of a gas flow control valve based on the deviation, so that the working gas is transferred between the first cryogenic thermostat and the second cryogenic thermostat under the drive of the pressure difference; acquiring the actual pressure of the first cryogenic thermostat in real time, and dynamically adjusting the temperature of the second cryogenic thermostat and the opening of the gas flow control valve based on the real-time updated deviation, until the actual pressure of the first cryogenic thermostat is controlled at the target pressure.

[0014] According to the fully enclosed microfluidic pressure control method provided by the present invention, the active temperature control unit is controlled to adjust the temperature of the second low-temperature thermostat according to the deviation, including: when the actual pressure is greater than the target pressure, the active temperature control unit is controlled to reduce the temperature of the second low-temperature thermostat, so as to reduce the internal pressure of the second low-temperature thermostat, so as to establish a positive pressure difference from the first low-temperature thermostat to the second low-temperature thermostat between the second low-temperature thermostat and the first low-temperature thermostat.

[0015] According to the present invention, a fully enclosed microfluidic pressure control method is provided, which controls the active temperature control unit to adjust the temperature of the second low-temperature thermostat according to the deviation, including: when the actual pressure is less than the target pressure, controlling the active temperature control unit to raise the temperature of the second low-temperature thermostat, so as to increase the internal pressure of the second low-temperature thermostat, so as to establish a reverse pressure difference between the second low-temperature thermostat and the first low-temperature thermostat.

[0016] According to the present invention, a fully enclosed microfluidic pressure control method dynamically adjusts the temperature of a second cryogenic thermostat and the opening of a gas flow control valve based on real-time updated deviations. The method includes: using the actual pressure of a first cryogenic thermostat as a feedback signal, calculating a target flow value through a pressure control loop; and using the actual flow value detected by a gas flow meter installed on the connecting pipeline as a feedback signal, adjusting the opening of the gas flow control valve based on the deviation between the target flow value and the actual flow value through a flow control loop.

[0017] According to the present invention, a fully enclosed microfluidic pressure control method dynamically adjusts the temperature and gas flow control valve opening of a second cryogenic thermostat based on real-time updated deviations. The method includes: when the actual pressure of the first cryogenic thermostat approaches the target pressure, reducing the opening of the gas flow control valve to decrease the transfer rate of the working gas between the first and second cryogenic thermostats; adjusting the power of the active temperature control unit to change the temperature of the second cryogenic thermostat, maintaining a preset temperature difference between the second and first cryogenic thermostats; and using the pressure difference generated by the preset temperature difference to continuously transfer the working gas in the fully enclosed gas circuit, maintaining the gas flow control valve opening at a position where the pressure difference overcomes the flow resistance of the connecting pipe, thereby locking the internal pressure of the first cryogenic thermostat at the target pressure. The fully enclosed gas circuit is composed of a connecting pipe linking the gas phase space of the first and second cryogenic thermostats.

[0018] The fully enclosed microfluidic pressure control system and method provided by this invention connects the gas phase spaces of a first cryogenic thermostat and a second cryogenic thermostat via a connecting pipe to form a fully enclosed gas loop. This allows the working gas to circulate only within the loop and remain isolated from the external environment, achieving zero-loss recycling of the working gas. Based on this, the central control system, according to the deviation between the actual pressure and the target pressure of the first cryogenic thermostat, controls the active temperature control unit to adjust the temperature of the second cryogenic thermostat. Utilizing the physical property that saturated vapor pressure changes with temperature, a pressure difference corresponding to the direction of deviation is established between the two thermostats. This pressure difference serves as the driving force for gas transfer, exhibiting a smooth and pulsation-free characteristic. Its dynamic and electromagnetic interference-free characteristics eliminate the need for differential control, which relies on the absolute accuracy matching of two flow meters, as in traditional solutions. This frees control accuracy from the limitations of the synchronization and long-term drift of multiple flow meters. Furthermore, the central control system controls the opening of the gas flow control valve based on the same deviation. The direction of the deviation determines the direction of gas transfer, and the magnitude of the deviation determines the valve opening. This allows the working gas to be directionally transferred along the connecting pipeline in a fully enclosed gas loop under the drive of differential pressure, achieving a precise response of the gas transfer direction and amount to pressure deviation. Finally, through closed-loop iteration, the system adaptively converges to an equilibrium state, achieving long-term stable high-precision pressure control. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a fully enclosed microfluidic pressure control system provided in an embodiment of the present invention.

[0021] Figure 2 This is a schematic flowchart of a fully enclosed microfluidic pressure control method provided in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] Figure 1 This is a schematic diagram of a fully enclosed microfluidic pressure control system provided in an embodiment of the present invention.

[0024] like Figure 1 As shown, the fully enclosed microfluidic pressure control system includes: a first low-temperature thermostat 110, a second low-temperature thermostat 120, a connecting pipeline 130, a gas flow control valve 140, an active temperature control unit 150, and a central control system 160.

[0025] In this embodiment of the invention, the connecting pipe 130 connects the gas phase space of the first low-temperature thermostat 110 and the gas phase space of the second low-temperature thermostat 120, forming a fully enclosed gas circuit.

[0026] For example, the connecting pipe 130 is a capillary metal tube, and its two ends are respectively sealed to the gas phase space of the first low temperature thermostat 110 and the second low temperature thermostat 120, so that the gas phase space of the two thermostats are interconnected through the capillary metal tube, forming a closed gas passage that is completely isolated from the external environment.

[0027] Specifically, at least a portion of the connecting pipe 130 is located in a room temperature environment to facilitate the installation and maintenance of various components on the pipe at room temperature, while avoiding the adverse effects of low temperature environment on the performance of precision components such as valves and flow meters.

[0028] Optionally, the working gas in the fully enclosed gas circuit can be helium-3 gas.

[0029] For example, the working gas is a high-purity helium-3 isotope gas. Helium-3 gas has an extremely low saturated vapor pressure under extremely low temperature conditions, making it suitable for precision pressure control scenarios in the milliKelvin temperature range.

[0030] Specifically, after the fully enclosed gas circuit is evacuated to a high vacuum at room temperature, it is filled with a preset amount of high-purity working gas to keep the total amount of gas in the circuit constant and prevent gas exchange with the external environment during subsequent operation.

[0031] Optionally, the first cryogenic thermostat 110 and the second cryogenic thermostat 120 have the same structure, volume and materials.

[0032] For example, the first cryogenic thermostat 110 and the second cryogenic thermostat 120 are sealed containers with identical structure, volume and materials, and both are filled with the same working gas, forming a symmetrical design.

[0033] The first low-temperature thermostat 110 serves as the target object for pressure control, used to maintain the preset working temperature and internal pressure; the second low-temperature thermostat 120 serves as the driving source for pressure regulation, used to generate differential pressure driving force through temperature changes.

[0034] Specifically, the symmetrical design ensures that the system has symmetrical dynamic response characteristics during bidirectional gas transfer regulation. That is, whether the gas is transferred from the first cryogenic thermostat 110 to the second cryogenic thermostat 120 or from the second cryogenic thermostat 120 to the first cryogenic thermostat 110, the system's response speed and regulation accuracy remain consistent.

[0035] Thus, by employing two completely symmetrical cryogenic thermostats to form a fully enclosed loop, this invention enables the system to have symmetrical dynamic characteristics during bidirectional regulation, thereby improving the consistency and stability of pressure control.

[0036] In this embodiment of the invention, a gas flow control valve 140 is disposed on a connecting pipeline 130.

[0037] For example, the gas flow control valve 140 is a proportional valve, which is connected in series in the connecting pipe 130. It can continuously adjust the valve opening according to the control command, thereby controlling the gas flow rate through the connecting pipe 130.

[0038] Specifically, the gas flow control valve 140 has high-speed response characteristics and can complete the opening adjustment in a short time according to the control signal to adapt to the precise control requirements of micro-flow gas and ensure that the gas transfer rate can be adjusted in real time to follow the changes in pressure deviation.

[0039] In this embodiment of the invention, the active temperature control unit 150 is thermally coupled to the second low-temperature thermostat 120.

[0040] For example, the active temperature control unit 150 includes a heating element and a temperature sensing element, both of which are thermally coupled to the cold head of the second low-temperature thermostat 120 for actively adjusting the internal temperature of the second low-temperature thermostat 120.

[0041] Specifically, the heating element is used to input heat into the second cryogenic thermostat 120 to raise its internal temperature; the temperature sensing element is used to detect the actual temperature of the second cryogenic thermostat 120 in real time and feed the temperature signal back to the control system to form a temperature closed loop. By adjusting the power of the heating element, the temperature of the second cryogenic thermostat 120 can be precisely controlled, thereby changing the saturated vapor pressure of its internal working gas.

[0042] In this embodiment of the invention, the central control system 160 is connected to the pressure detection terminal of the first low-temperature thermostat 110, the gas flow control valve 140, and the active temperature control unit 150, respectively.

[0043] For example, the central control system 160, as the control center of the entire system, is responsible for collecting the detection signals of each sensor, running the preset control algorithm, and outputting control commands to each actuator to achieve fully automatic and adaptive pressure control.

[0044] Specifically, the input signals of the central control system 160 include the pressure signal of the first low-temperature thermostat 110 and the temperature signal of the active temperature control unit 150; the output signals of the central control system 160 include the temperature adjustment command output to the active temperature control unit 150 and the opening adjustment command output to the gas flow control valve 140.

[0045] In some embodiments, the central control system 160 is configured to control the active temperature control unit 150 to adjust the temperature of the second low-temperature thermostat 120 to generate a pressure difference based on the deviation between the actual pressure and the target pressure of the first low-temperature thermostat 110.

[0046] For example, the central control system 160 acquires the actual pressure value of the first low-temperature thermostat 110 in real time, compares the actual pressure value with the preset pressure target value, and obtains a pressure deviation signal; according to the direction and magnitude of the pressure deviation signal, it outputs a temperature adjustment command to the active temperature control unit 150 to adjust the internal temperature of the second low-temperature thermostat 120, and utilizes the physical characteristics of the working gas saturated vapor pressure changing with temperature to establish a controllable pressure difference between the two thermostats corresponding to the direction of the pressure deviation.

[0047] Specifically, when the actual pressure value is greater than the preset pressure target value, the central control system 160 outputs a cooling command to the active temperature control unit 150 to reduce the temperature of the second low-temperature thermostat 120, so that the saturated vapor pressure in the second low-temperature thermostat 120 is lower than the internal pressure of the first low-temperature thermostat 110, thus establishing a positive pressure difference from the first low-temperature thermostat 110 to the second low-temperature thermostat 120; when the actual pressure value is less than the preset pressure target value, the central control system 160 outputs a heating command to the active temperature control unit 150 to increase the temperature of the second low-temperature thermostat 120, so that the saturated vapor pressure in the second low-temperature thermostat 120 is higher than the internal pressure of the first low-temperature thermostat 110, thus establishing a reverse pressure difference from the second low-temperature thermostat 120 to the first low-temperature thermostat 110.

[0048] In other embodiments, the central control system 160 is used to control the opening of the valve 140 according to the deviation control gas flow, so that the working gas is transferred in a fully enclosed gas circuit to regulate the internal pressure of the first cryogenic thermostat 110.

[0049] For example, the central control system 160 outputs an opening adjustment command to the gas flow control valve 140 according to the pressure deviation signal, so that the gas flow control valve 140 opens to the corresponding opening. Under the drive of the controllable pressure difference, the working gas is directionally transferred between the two thermostats through the connecting pipeline 130 to reduce the pressure deviation.

[0050] Specifically, the direction of the pressure deviation determines the direction of gas transfer, and the magnitude of the pressure deviation determines the valve opening and the gas transfer rate; the larger the deviation, the larger the valve opening and the faster the gas transfer rate, thus achieving a precise correspondence between the pressure deviation and the amount of gas transferred.

[0051] In the fully enclosed microfluidic pressure control system provided by this invention, a fully enclosed gas loop is formed by connecting the gas phase spaces of the first and second cryogenic thermostats through a connecting pipe. This allows the working gas to circulate only within the loop and be isolated from the external environment, achieving zero-loss recycling of the working gas. Based on this, the central control system, according to the deviation between the actual pressure and the target pressure of the first cryogenic thermostat, controls the active temperature control unit to adjust the temperature of the second cryogenic thermostat. Utilizing the physical property that saturated vapor pressure changes with temperature, a pressure difference corresponding to the direction of deviation is established between the two thermostats. This pressure difference serves as the driving force for gas transfer, exhibiting a smooth and pulsation-free characteristic. Its dynamic and electromagnetic interference-free characteristics eliminate the need for differential control, which relies on the absolute accuracy matching of two flow meters, as in traditional solutions. This frees control accuracy from the limitations of the synchronization and long-term drift of multiple flow meters. Furthermore, the central control system controls the opening of the gas flow control valve based on the same deviation. The direction of the deviation determines the direction of gas transfer, and the magnitude of the deviation determines the valve opening. This allows the working gas to be directionally transferred along the connecting pipeline in a fully enclosed gas loop under the drive of differential pressure, achieving a precise response of the gas transfer direction and amount to pressure deviation. Finally, through closed-loop iteration, the system adaptively converges to an equilibrium state, achieving long-term stable high-precision pressure control.

[0052] Optionally, the fully enclosed microfluidic pressure control system provided by the present invention further includes a gas flow meter 170.

[0053] In this embodiment of the invention, a gas flow meter 170 is installed on the connecting pipe 130 and is connected to the central control system 160 for detecting the gas flow rate in the connecting pipe 130.

[0054] For example, a gas flow meter 170 is connected in series in the room temperature section of the connecting pipe 130 to monitor the gas flow rate and direction through the connecting pipe 130 in real time, and outputs the flow detection signal to the central control system 160 as a feedback variable for flow closed-loop control.

[0055] Specifically, the gas flow meter 170 can not only detect the magnitude of the gas flow, but also the direction of gas flow, thereby determining whether the gas flows from the first low-temperature thermostat 110 to the second low-temperature thermostat 120 or from the second low-temperature thermostat 120 to the first low-temperature thermostat 110, providing feedback for precise bidirectional flow control.

[0056] Thus, by installing a gas flow meter on the connecting pipeline, the present invention enables real-time monitoring of the gas transfer process, provides feedback signals for flow closed-loop control, and further improves the accuracy and stability of pressure control.

[0057] Optionally, the fully enclosed microfluidic pressure control system provided by the present invention also includes a volume regulator.

[0058] In this embodiment of the invention, a volume regulator is connected to the gas phase space of the second cryogenic thermostat 120 and is used to adjust the gas pressure inside the second cryogenic thermostat 120 by changing the volume.

[0059] For example, the volume regulator is a sealing device that can change its internal volume. It is in sealed communication with the gas phase space of the second cryogenic thermostat 120. By changing its own effective volume, it directly changes the gas pressure on the side of the second cryogenic thermostat 120, thereby establishing a pressure difference between the two thermostats.

[0060] Specifically, the volume regulator provides a different method of generating differential pressure than the active temperature control unit 150, that is, generating differential pressure through volume change rather than temperature change; this method can reduce thermal disturbance and has a faster response speed, and can be used as a substitute or supplement to the active temperature control method.

[0061] Optionally, the volume regulator can be a bellows volume regulator; the bellows volume regulator is driven by an external micro-displacement mechanism to achieve volume change.

[0062] For example, the bellows volume regulator includes a fully sealed bellows cavity and an external micro-displacement drive mechanism. The interior of the bellows cavity is in sealed communication with the gas phase space of the second cryogenic thermostat 120. The external micro-displacement drive mechanism is used to drive the bellows to produce expansion and contraction deformation, thereby changing the effective volume of the cavity and thus regulating the gas pressure.

[0063] Thus, by setting up a volume regulator, the present invention provides another way to generate differential pressure, which can reduce thermal disturbance and improve response speed, enriching the system's control methods and applicable scenarios.

[0064] Optionally, the central control system 160 is also connected to the volume regulator signal.

[0065] In some embodiments, the central control system 160 is configured to control the volume regulator to change the volume of the second cryogenic thermostat 120 to generate a pressure differential based on the deviation between the actual pressure and the target pressure of the first cryogenic thermostat 110.

[0066] For example, when the volume regulation method is adopted, the central control system 160 outputs a volume regulation command to the volume regulator according to the pressure deviation signal, and establishes a controllable pressure difference between the two thermostats corresponding to the deviation direction by changing the effective volume on the side of the second low temperature thermostat 120.

[0067] Specifically, when it is necessary to reduce the pressure of the first low-temperature thermostat 110, the central control system 160 controls the volume regulator to increase the volume, thereby reducing the gas pressure on the side of the second low-temperature thermostat 120 and establishing a positive pressure difference; when it is necessary to increase the pressure of the first low-temperature thermostat 110, the volume regulator controls the volume regulator to decrease the volume, thereby increasing the gas pressure on the side of the second low-temperature thermostat 120 and establishing a reverse pressure difference.

[0068] In other embodiments, the central control system 160 is used to control the opening of the valve 140 according to the deviation control gas flow, so that the working gas is transferred in a fully enclosed gas circuit to regulate the internal pressure of the first cryogenic thermostat 110.

[0069] For example, in the volume regulation mode, the central control system 160 also controls the opening of the gas flow control valve 140 according to the pressure deviation signal, so that the working gas is directionally transferred between the two thermostats under the pressure difference generated by the volume change, so as to regulate the internal pressure of the first low temperature thermostat 110.

[0070] Specifically, the valve control logic under volume regulation is consistent with that under temperature regulation. Both determine the valve opening and gas transfer rate based on the direction and magnitude of the pressure deviation, thus ensuring the uniformity of the control logic under the two pressure difference generation methods.

[0071] Thus, the present invention generates pressure difference through volume adjustment, which can reduce thermal disturbance and improve response speed, providing another efficient control method for the system.

[0072] The following is combined Figure 2 This invention describes a fully enclosed microfluidic pressure control method. For consistency, the entity executing this method will be uniformly referred to as the system, and will not be described further thereafter.

[0073] Figure 2 This is a schematic flowchart of the fully enclosed microfluidic pressure control method provided in an embodiment of the present invention. Figure 2 As shown, the method includes the following steps: S201. Obtain the deviation between the actual pressure and the target pressure of the first low-temperature thermostat.

[0074] In some embodiments, a pressure sensor installed on the first low-temperature thermostat can be used to read the actual pressure value inside the first low-temperature thermostat in real time using a high-frequency sampling method, and the actual pressure value can be compared with a preset pressure target value to calculate the deviation between the two.

[0075] For example, the pressure signal of the first low-temperature thermostat is continuously acquired at a preset sampling frequency, and the actual pressure value at the current moment is recorded as... The preset target pressure value is recorded as The pressure deviation was calculated. and the rate of change of deviation, of which Indicates the current moment.

[0076] Specifically, this can be calculated using an internal PID controller. and deviation and the rate of change of deviation.

[0077] S202. Based on the deviation, control the active temperature control unit to adjust the temperature of the second low-temperature thermostat, so that a pressure difference corresponding to the direction of the deviation is generated between the second low-temperature thermostat and the first low-temperature thermostat.

[0078] In one optional implementation, when the actual pressure is greater than the target pressure, the active temperature control unit is controlled to reduce the temperature of the second low-temperature thermostat, thereby reducing the internal pressure of the second low-temperature thermostat and establishing a positive pressure difference between the second low-temperature thermostat and the first low-temperature thermostat, pointing from the first low-temperature thermostat to the second low-temperature thermostat.

[0079] For example, when the actual pressure of the first cryostat is detected greater than target pressure When this occurs, it indicates that gas needs to be transferred out of the first cryogenic thermostat to reduce the pressure; at this time, a cooling command is sent to the active temperature control unit to further cool the second cryogenic thermostat.

[0080] Specifically, according to thermodynamic principles, a decrease in temperature will cause a drop in the saturated vapor pressure of the working gas inside the second cryogenic thermostat, thereby reducing the internal pressure of the second cryogenic thermostat. Lower than the internal pressure of the first cryostat ,Right now Thus, a positive pressure difference is established between the two thermostats, pointing from the first cryogenic thermostat to the second cryogenic thermostat. This pressure difference serves as the driving force for the transfer of gas from the first cryogenic thermostat to the second cryogenic thermostat.

[0081] Thus, by reducing the temperature of the second cryogenic thermostat when the actual pressure is greater than the target pressure, this invention utilizes the physical property that the saturated vapor pressure decreases with decreasing temperature to establish a positive pressure difference as the driving force for the outward transfer of gas, providing a physical basis for pressure reduction regulation.

[0082] In another alternative implementation, when the actual pressure is less than the target pressure, the active temperature control unit raises the temperature of the second low-temperature thermostat, causing the internal pressure of the second low-temperature thermostat to rise, so as to establish a reverse pressure difference between the second low-temperature thermostat and the first low-temperature thermostat.

[0083] For example, when the actual pressure of the first cryostat is detected Less than target pressure When the pressure is high, it indicates that gas needs to be added to the first low-temperature thermostat to increase the pressure; at this time, a heating command is sent to the active temperature control unit to appropriately increase the temperature of the second low-temperature thermostat.

[0084] Specifically, an increase in temperature will cause the saturated vapor pressure of the working gas inside the second cryogenic thermostat to rise, thereby increasing the internal pressure of the second cryogenic thermostat. The internal pressure is higher than that of the first cryogenic thermostat. ,Right now Thus, a reverse pressure difference is established between the two thermostats, pointing from the second cryogenic thermostat to the first cryogenic thermostat. This pressure difference serves as the driving force for the transfer of gas from the second cryogenic thermostat to the first cryogenic thermostat.

[0085] Thus, by raising the temperature of the second cryogenic thermostat when the actual pressure is less than the target pressure, this invention utilizes the physical property that the saturated vapor pressure increases with increasing temperature to establish a reverse pressure difference as the driving force for gas to replenish itself, providing a physical basis for pressure boosting control.

[0086] S203. Based on the deviation, control the opening of the gas flow control valve so that the working gas is transferred between the first low-temperature thermostat and the second low-temperature thermostat under the drive of the pressure difference.

[0087] In some embodiments, the required gas transfer amount and transfer rate can be calculated based on the direction and magnitude of the pressure deviation, and a corresponding opening adjustment command can be output to the gas flow control valve to open the valve at an appropriate opening.

[0088] For example, the target opening of the gas flow control valve is determined based on the output value of the PID control algorithm; the larger the deviation, the larger the valve opening and the faster the gas transfer rate; the smaller the deviation, the smaller the valve opening and the slower the gas transfer rate, thereby achieving a precise match between the gas transfer amount and the pressure deviation.

[0089] Specifically, driven by a positive pressure differential, the working gas flows from the first cryogenic thermostat into the second cryogenic thermostat via a connecting pipe, causing the actual pressure in the first cryogenic thermostat to drop back towards the target pressure. Driven by a reverse pressure differential, the working gas flows from the second cryogenic thermostat back to the first cryogenic thermostat via the connecting pipe, causing the actual pressure in the first cryogenic thermostat to rise back towards the target pressure. The entire gas transfer process is completed within a fully enclosed gas loop, with no gas being released to the outside of the system.

[0090] S204. The actual pressure of the first low-temperature thermostat is obtained in real time, and the opening of the temperature and gas flow control valve of the second low-temperature thermostat is dynamically adjusted according to the real-time updated deviation until the actual pressure of the first low-temperature thermostat is controlled at the target pressure.

[0091] In this embodiment of the invention, the actual pressure of the first low-temperature thermostat can be used as a feedback signal to calculate the target flow rate value through the pressure control loop.

[0092] For example, a dual closed-loop control structure can be adopted, wherein the outer loop is a pressure control loop, the actual pressure value of the first low-temperature thermostat is used as the feedback input, the deviation between the actual pressure and the target pressure is used as the input, and the target flow setpoint is calculated by the control algorithm.

[0093] Specifically, the pressure control loop determines the target gas flow rate to be transferred based on the magnitude of the pressure deviation, i.e., how quickly the gas needs to be transferred to rapidly bring the pressure close to the target value; the target flow rate setpoint serves as the input to the inner flow control loop.

[0094] Furthermore, the actual flow rate detected by the gas flow meter installed on the connecting pipeline is used as a feedback signal, and the opening of the gas flow control valve is adjusted by the flow control loop according to the deviation between the target flow rate and the actual flow rate.

[0095] For example, the inner loop is a flow control loop, which uses the actual flow value detected by the gas flow meter as the feedback input, and the deviation between the target flow setpoint and the actual flow value as the input. The control algorithm calculates the opening adjustment command of the gas flow control valve.

[0096] Specifically, the function of the flow control loop is to precisely control the actual flow rate of gas transfer, enabling it to quickly track the target flow rate setpoint. Because the flow control loop responds faster than the pressure control loop, it can effectively suppress flow fluctuations caused by factors such as changes in pipeline flow resistance, thereby improving the accuracy and stability of pressure control.

[0097] Thus, by employing a double closed-loop nested structure of outer-loop pressure control and inner-loop flow control, this invention ensures both the macroscopic accuracy of pressure control and the microscopic precision of flow control, thereby improving control accuracy and dynamic response capability.

[0098] Optionally, when the actual pressure of the first cryogenic thermostat approaches the target pressure, the opening of the gas flow control valve is reduced to decrease the transfer rate of the working gas between the first and second cryogenic thermostats.

[0099] For example, as the actual pressure value of the first low-temperature thermostat gradually approaches the preset pressure target value, the pressure deviation gradually decreases, and the opening of the gas flow control valve is gradually reduced accordingly to decrease the gas transfer rate, so as to avoid pressure overshoot caused by inertia.

[0100] Specifically, as the pressure deviation decreases, the output of the PID control algorithm gradually decreases, the valve opening gradually closes, and the gas transfer rate gradually decreases. This gradual adjustment method enables the pressure to smoothly approach the target value, reducing oscillations and overshoot during the adjustment process.

[0101] Furthermore, the power of the active temperature control unit can be adjusted to change the temperature of the second low-temperature thermostat, so that a preset temperature difference is maintained between the second low-temperature thermostat and the first low-temperature thermostat.

[0102] For example, as the pressure approaches stability, the output power of the active temperature control unit is adjusted synchronously to gradually stabilize the temperature of the second low-temperature thermostat at a specific value, thereby maintaining a small but stable temperature difference between the two thermostats.

[0103] Specifically, the pressure difference generated by the tiny temperature difference is just enough to overcome the flow resistance of the connecting pipe and maintain a very small and stable airflow. At this time, a dynamic equilibrium state is reached, that is, the pressure difference that just overcomes the pipe resistance is maintained by a tiny temperature difference, and the valve opening tends to maintain the minimum value of this micro-flow state.

[0104] Furthermore, the working gas is continuously transferred in a fully enclosed gas circuit by the pressure difference generated by the preset temperature difference, and the opening of the gas flow control valve is maintained at a position where the pressure difference overcomes the flow resistance of the connecting pipeline, so as to lock the internal pressure of the first low temperature thermostat at the target pressure.

[0105] For example, once dynamic equilibrium is reached, a stable, small temperature difference is maintained between the second cryogenic thermostat and the first cryogenic thermostat. The pressure difference generated by this temperature difference just overcomes the flow resistance of the connecting pipe, forming a stable micro-flow. The gas flow control valve is maintained at a small opening to maintain this micro-flow state.

[0106] Specifically, in this dynamic equilibrium state, the internal pressure of the first cryogenic thermostat is precisely locked at the target pressure value, and the pressure fluctuation is controlled within a very small range; throughout the entire equilibrium process, the working gas always circulates within a fully enclosed gas circuit, and no gas is discharged to the outside of the system.

[0107] Thus, by gradually reducing the valve opening and simultaneously adjusting the temperature control power as the pressure approaches the target value, the present invention enables the system to eventually reach a dynamic equilibrium state maintained by a small temperature difference, which not only ensures high precision of pressure control but also achieves zero-loss recycling of the working gas.

[0108] In the fully enclosed microfluidic pressure control method provided in this embodiment of the invention, the deviation between the actual pressure and the target pressure of the first cryogenic thermostat is obtained, providing an accurate input basis for subsequent regulation. Based on this, the temperature of the second cryogenic thermostat is adjusted by the active temperature control unit according to the deviation. The physical property of saturated vapor pressure changing with temperature is used to establish a pressure difference in the direction corresponding to the deviation, so that the driving force direction is precisely matched with the regulation requirements. Then, the opening of the valve is controlled by the gas flow rate according to the same deviation. The deviation direction determines the gas transfer direction, and the deviation magnitude determines the valve opening size, so that the working gas is directionally transferred along the connecting pipeline under the pressure difference drive, realizing the accurate response of the transfer direction and transfer amount to the pressure deviation. Finally, by obtaining the actual pressure of the first cryogenic thermostat in real time and dynamically adjusting the temperature and valve opening according to the real-time updated deviation, a fully closed-loop adaptive iterative mechanism is formed until the pressure stabilizes at the target value. This allows the system to automatically converge to an equilibrium state during the entire regulation process, thereby achieving high-precision and long-term stable pressure control while realizing zero-loss recycling of the working gas.

[0109] It should be noted that the fully enclosed microfluidic pressure control system and method provided in this embodiment of the invention are not only applicable to helium-3 gas systems, but their core concept of fully enclosed and active differential pressure regulation is also applicable to any scenario that requires high-precision, zero-loss pressure control of trace amounts of precious or dangerous gases in a closed space.

[0110] For example, precision gas analysis, standard gas preparation, and the packaging and control of radioactive gases.

[0111] For example, in terms of control strategy, the active temperature control unit and valve of the present invention can be replaced by advanced algorithms such as model predictive control in addition to PID control algorithm. Model predictive control can predict temperature changes and pressure response in advance based on the system thermodynamic model, thereby achieving better convergence speed while avoiding pressure overshoot.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fully enclosed microfluidic pressure control system, characterized in that, The system includes: First low-temperature thermostat and second low-temperature thermostat; A connecting pipe is used to connect the gas phase space of the first low-temperature thermostat and the gas phase space of the second low-temperature thermostat to form a fully enclosed gas circuit. A gas flow control valve is installed on the connecting pipeline; An active temperature control unit is thermally coupled to the second low-temperature thermostat. The central control system is connected to the pressure detection terminal of the first low-temperature thermostat, the gas flow control valve, and the active temperature control unit, respectively. The central control system is used for: Based on the deviation between the actual pressure and the target pressure of the first low-temperature thermostat, the active temperature control unit is controlled to adjust the temperature of the second low-temperature thermostat to generate a pressure difference. The opening degree of the gas flow control valve is controlled according to the deviation, so that the working gas is transferred in the fully enclosed gas circuit to regulate the internal pressure of the first cryogenic thermostat.

2. The system according to claim 1, characterized in that, The first cryogenic thermostat has the same structure, volume and materials as the second cryogenic thermostat.

3. The system according to claim 1, characterized in that, The system also includes a gas flow meter; The gas flow meter is installed on the connecting pipeline and is connected to the central control system for detecting the gas flow rate in the connecting pipeline.

4. The system according to claim 1, characterized in that, The system also includes a volume regulator; The volume regulator is connected to the gas phase space of the second cryogenic thermostat and is used to adjust the gas pressure inside the second cryogenic thermostat by changing its volume.

5. The system according to claim 4, characterized in that, The central control system is also connected to the volume regulator via a signal connection. The central control system is used for: Based on the deviation between the actual pressure and the target pressure of the first cryogenic thermostat, the volume regulator is controlled to change the volume of the second cryogenic thermostat to generate a pressure difference. The opening degree of the gas flow control valve is controlled according to the deviation, so that the working gas is transferred in the fully enclosed gas circuit to regulate the internal pressure of the first cryogenic thermostat.

6. A fully enclosed microfluidic pressure control method, characterized in that, The method includes: Obtain the deviation between the actual pressure and the target pressure of the first cryogenic thermostat; Based on the deviation, the active temperature control unit is controlled to adjust the temperature of the second low-temperature thermostat, so that a pressure difference corresponding to the direction of the deviation is generated between the second low-temperature thermostat and the first low-temperature thermostat. Based on the deviation, the opening of the gas flow control valve is controlled so that the working gas is transferred between the first cryogenic thermostat and the second cryogenic thermostat under the drive of the pressure difference. The actual pressure of the first low-temperature thermostat is acquired in real time, and the temperature of the second low-temperature thermostat and the opening of the gas flow control valve are dynamically adjusted according to the real-time updated deviation until the actual pressure of the first low-temperature thermostat is controlled at the target pressure.

7. The method according to claim 6, characterized in that, The step of controlling the active temperature control unit to adjust the temperature of the second low-temperature thermostat according to the deviation includes: When the actual pressure is greater than the target pressure, the active temperature control unit is controlled to reduce the temperature of the second low-temperature thermostat, thereby reducing the internal pressure of the second low-temperature thermostat and establishing a positive pressure difference between the second low-temperature thermostat and the first low-temperature thermostat, pointing from the first low-temperature thermostat to the second low-temperature thermostat.

8. The method according to claim 6, characterized in that, The step of controlling the active temperature control unit to adjust the temperature of the second low-temperature thermostat according to the deviation includes: When the actual pressure is less than the target pressure, the active temperature control unit is controlled to raise the temperature of the second low-temperature thermostat, thereby increasing the internal pressure of the second low-temperature thermostat and establishing a reverse pressure difference between the second low-temperature thermostat and the first low-temperature thermostat, pointing from the second low-temperature thermostat to the first low-temperature thermostat.

9. The method according to claim 6, characterized in that, The step of dynamically adjusting the temperature of the second cryogenic thermostat and the opening of the gas flow control valve based on the real-time updated deviation includes: The target flow rate is calculated by using the actual pressure of the first low-temperature thermostat as a feedback signal through the pressure control loop. Using the actual flow rate detected by the gas flow meter installed on the connecting pipeline as a feedback signal, the opening of the gas flow control valve is adjusted by the flow control loop according to the deviation between the target flow rate and the actual flow rate.

10. The method according to claim 6, characterized in that, The step of dynamically adjusting the temperature of the second cryogenic thermostat and the opening of the gas flow control valve based on the real-time updated deviation includes: When the actual pressure of the first cryogenic thermostat approaches the target pressure, the opening of the gas flow control valve is reduced to decrease the transfer rate of the working gas between the first cryogenic thermostat and the second cryogenic thermostat. Adjust the power of the active temperature control unit to change the temperature of the second low-temperature thermostat, so that the second low-temperature thermostat and the first low-temperature thermostat maintain a preset temperature difference; The working gas is continuously transferred in the fully enclosed gas circuit by the pressure difference generated by the preset temperature difference. The opening of the gas flow control valve is maintained at a position that allows the pressure difference to overcome the flow resistance of the connecting pipeline, so as to lock the internal pressure of the first low temperature thermostat at the target pressure. The fully enclosed gas circuit is composed of the gas phase space of the first low-temperature thermostat and the gas phase space of the second low-temperature thermostat connected by the connecting pipe.

Images