A thermostat device capable of performing continuous temperature control in a wide temperature range

Abstract

The present invention discloses a thermostat device capable of performing continuous temperature control over a wide temperature range, the device comprising a low temperature refrigeration system, a sample chamber assembly, a heat insulation assembly and a sample temperature control system, wherein a sample rod body (43) in the sample chamber assembly is provided with a sample temperature sensor (54) and a sample heater (55) respectively connected to a temperature controller (57) in the sample temperature control system, the temperature controller (57) is connected to a host computer (56) via a line, and the host computer (56) performs PID closed-loop control on the sample temperature sensor (54) and the sample heater (55) via the temperature controller (57); a static helium pressure sensor (64) connected to the host computer (56) is provided on a static helium pipeline connected to a static helium interface (47) in the sample chamber assembly. The device of the present invention can perform continuous temperature control over a wide temperature range of 2-800K, meeting the needs of today's high-end physical property measurement field.

Description

Technical Field

[0001] The invention belongs to the research field of cryogenic instrument devices, cryogenic temperature control methods and physical property measurement technologies, and is specifically a thermostat device based on a small cryogenic refrigerator and utilizing liquid helium throttling for cooling, which can perform continuous temperature control over a wide temperature range. Background Art

[0002] Low temperature thermostats with temperature scanning function are often used in the field of physical property measurement. With the continuous development of material technology, more and more new materials have been successfully developed. In order to verify the properties of these materials, it is necessary to carry out physical property measurement. However, the application fields of these materials are very wide, and it is often necessary to measure their physical properties in a large range under the condition of an external magnetic field or radiation field, which puts higher requirements on the physical property measurement device. For thermostats used for physical property measurement, it is necessary to have a wider temperature range, more continuous temperature change, more open structure (to apply a specific physical field), and more precise temperature control.

[0003] At present, there is still a big gap between the research on cryostat in China and Europe, America and Japan, especially the wide temperature range below 4K for the measurement of physical properties of thermostats still leaves a large blank. At present, domestic patents have been published, such as CN105355319A, a cryostat for superconducting cables, CN205246278U, a low temperature working device, and CN207456918U, a liquid nitrogen cryostat. The lowest temperature stays in the liquid nitrogen temperature zone of about 77K. The structural design without an external physical field can no longer meet the existing high-end physical property measurement needs. For example, CN108800638A, a cryostat, and CN107655236A ultra-low vibration cryostat, although they can reach the 4K liquid helium temperature zone, are still far from the international leading refrigeration temperature; and because they have no overheating protection capability, they do not have the ability to operate in the high temperature zone. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of narrow temperature range, high lower limit of temperature range, discontinuous temperature change and the like of existing low-temperature thermostats, and to provide a thermostat device which is based on a small low-temperature refrigerator and utilizes liquid helium throttling for cooling and can perform continuous temperature change control over a wide temperature range. The device has a more open design and is convenient for adding a physical field to meet the requirements of various physical property measurement environments.

[0005] The purpose of the present invention is to be solved by the following technical solutions:

[0006] A thermostat device capable of performing continuous temperature control over a wide temperature range, characterized in that the device comprises a low-temperature refrigeration system, a sample chamber assembly, a thermal insulation assembly and a sample temperature control system; a sample temperature sensor and a sample heater are arranged on a sample rod body for placing a sample in the sample chamber assembly; the sample temperature sensor and the sample heater are respectively connected to a temperature controller in the sample temperature control system; the temperature controller is connected to a host computer through a line; the host computer performs PID closed-loop control on the sample temperature sensor and the sample heater through the temperature controller; a static helium pressure sensor for monitoring the static helium pressure is arranged on a static helium pipeline connected to a static helium interface for controlling the static helium pressure in the sample chamber assembly; the static helium pressure sensor is connected to the host computer to feed back the pressure of the static helium.

[0007] The cryogenic valve in the cryogenic refrigeration system is provided with a cryogenic valve control mechanism which is communicatively connected to a host computer. The host computer sets the stroke of the cryogenic valve needle of the cryogenic valve through the cryogenic valve control mechanism. The cryogenic valve control mechanism can feed back the stroke of the cryogenic valve needle to the host computer.

[0008] The liquid helium pipeline in the cryogenic refrigeration system is provided with a liquid helium temperature sensor and a liquid helium heater which can be controlled in linkage. The liquid helium temperature sensor and the liquid helium heater are respectively connected to a temperature controller, and the upper computer performs PID closed-loop control on the liquid helium temperature sensor and the liquid helium heater through the temperature controller.

[0009] A flow meter for monitoring the flow rate of circulating helium and a circulating helium pressure sensor for monitoring the pressure of circulating helium are arranged on the circulating helium pipeline in the low-temperature refrigeration system. The flow meter and the circulating helium pressure sensor are respectively connected to the host computer to feedback the flow rate and pressure of circulating helium. The flow meter is located at the rear side of the air outlet of the circulating pump on the circulating helium pipeline; the circulating helium pressure sensor is located at the front side of the air inlet of the circulating pump on the circulating helium pipeline.

[0010] Temperature monitoring points are respectively arranged on the primary heat radiation screen and the secondary heat radiation screen in the thermal insulation component, and the temperature sensors arranged at the temperature monitoring points are respectively connected to the temperature controller to feed back the real-time monitored temperature to the host computer; the vacuum cavity in the thermal insulation component is equipped with a vacuum pump, which is connected to the host computer so that the host computer can control the vacuum degree in the vacuum cavity through the vacuum pump.

[0011] The local downward protrusion of the heat-insulating component forms a heat-insulating sinking cavity to accommodate the sample cavity bottom cylinder in the sample cavity component, and the sample rod body in the sample cavity component extends into the sample cavity bottom cylinder.

[0012] The thermal insulation component comprises a vacuum cavity, a primary thermal radiation screen and a secondary thermal radiation screen, wherein the vacuum cavity is composed of a vacuum cavity flange and a vacuum cavity cylinder, and the bottom of the vacuum cavity cylinder is partially convex; the primary thermal radiation screen composed of the primary thermal radiation screen cylinder and the primary thermal radiation screen flange is suspended in the vacuum cavity, and the primary thermal radiation screen is provided with a primary thermal radiation screen lower extension section extending from the primary thermal radiation screen flange downward through the bottom of the primary thermal radiation screen cylinder and extending to the lower convex part of the vacuum cavity cylinder, the part of the primary thermal radiation screen lower extension section extending out of the bottom of the vacuum cavity cylinder and the lower convex part of the vacuum cavity cylinder constitute a thermal insulation sinking cavity; the secondary thermal radiation screen composed of the secondary thermal radiation screen cylinder and the secondary thermal radiation screen flange is suspended in the primary thermal radiation screen.

[0013] The low-temperature refrigeration system comprises a refrigerator, a refrigerator cavity, a cryogenic valve controlled by a cryogenic valve regulating mechanism, and a helium circulation system. The cold head of the refrigerator is inserted into the refrigerator cavity, and the refrigerator and the refrigerator cavity are thermally coupled by crimping. An elastic heat-conducting module is provided at the secondary cold head of the refrigerator to achieve thermal coupling with the refrigerator cavity bottom flange of the refrigerator cavity. The refrigerator cavity liquid helium outlet at the bottom of the refrigerator cavity is connected to the cryogenic valve liquid helium inlet on the cryogenic valve seat of the cryogenic valve located in the secondary heat radiation screen through a liquid helium pipeline in the secondary heat radiation screen in the heat insulation component. The cryogenic valve seat The cryogenic valve liquid helium outlet on the refrigerator is connected with the sample chamber liquid helium inlet at the bottom of the sample chamber sandwich in the sample chamber assembly through a pipeline, the circulating helium outlet at the top of the sample chamber sandwich is connected with the circulating helium inlet on the refrigerator chamber through a circulating helium pipeline with a circulating pump, and the refrigerator chamber, the liquid helium pipeline between the refrigerator chamber liquid helium outlet and the cryogenic valve liquid helium inlet, the inner cavity flow channel of the cryogenic valve seat, the pipeline between the cryogenic valve liquid helium outlet and the sample chamber liquid helium inlet, the sample chamber sandwich in the sample chamber assembly, and the circulating helium pipeline between the circulating helium outlet and the circulating helium inlet constitute a helium circulation system.

[0014] The elastic heat-conducting module is composed of a heat-conducting module top plate, a flexible heat-conducting chain, a spring, and a heat-conducting module bottom plate. The heat-conducting module top plate is in direct contact with the secondary cold head of the refrigerator, and the heat-conducting module bottom plate is in direct contact with the bottom flange of the refrigerator cavity. The heat-conducting module bottom plate and the heat-conducting module top plate are supported by springs and thermally coupled by a flexible heat-conducting chain.

[0015] The sample chamber assembly comprises a sample chamber outer tube, a sample chamber inner tube, a sample chamber bottom tube as an extension of the sample chamber inner tube, a sample chamber flange, a sample rod, and a sample rod flange. The sample rod body of the sample rod is inserted into the sample chamber inner tube and the sample chamber bottom tube, and the sample rod is fixed on the sample chamber flange through the sample rod flange. The sample rod body is evenly distributed with a rod body heat radiation screen. A sample chamber sandwich is formed between the sample chamber outer tube and the sample chamber inner tube. The low-temperature helium flow after the low-temperature valve flows through the sample chamber sandwich to cool the helium chamber formed by the sample chamber inner tube and the sample chamber bottom tube, and enters the circulating helium pipeline from the circulating helium outlet at the upper end of the sample chamber sandwich.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] The liquid helium throttling and cooling part of the device of the present invention adopts a self-designed cryogenic valve to replace the traditional capillary device. By changing the flow resistance of the throttling valve, not only the helium temperature and liquid helium ratio after throttling can be regulated, but also the helium flow rate can be fine-tuned. Therefore, the regulation and redistribution of cooling capacity can be achieved without significantly changing the temperature of the refrigerator. The device can provide a low-temperature environment of 2K for the sample by combining a 4K GM refrigerator with a JT valve. Compared with a thermostat using a single refrigerator, it has a lower low-temperature zone.

[0018] The sample chamber assembly of the present invention is provided with a sample chamber interlayer, and dynamic low-temperature helium passes through the sample chamber interlayer, and conducts heat with the sample through the static helium in the helium chamber, so that the heat conduction between the cold source and the sample can be controlled by adjusting the static helium pressure in the helium chamber; when operating in the low-temperature zone, the static helium pressure can be adjusted to increase to enhance heat exchange; when operating in the high-temperature zone, the static helium pressure is adjusted as low as possible to weaken heat exchange; in addition, the circulating helium in the sample chamber interlayer can be used to cool the wall surface of the sample chamber outer tube and the sample chamber inner tube, play a temperature protection role, and prevent the wall surface of the sample chamber from overheating and damaging the equipment; therefore, the device has a higher high-temperature temperature zone compared with other thermostat devices; that is, the device has the advantage of a wider temperature zone.

[0019] The device of the present invention adopts low-temperature-high-temperature zone segmented temperature control. The low-temperature zone and the high-temperature zone are further divided into a plurality of small temperature zones. Different PID closed-loop control parameters are set for each small temperature zone to control the heater. With the overall control of the software, a smooth transition between the temperature zones is achieved, and finally the continuous temperature change of the device is achieved and the sample temperature change rate is adjustable.

[0020] The sample temperature control system in the device of the present invention has an emergency processing function. When the temperature of other monitoring points in the thermostat device, except the sample position, exceeds the normal temperature to a certain extent, the host computer will alarm and cut off the power supply of the sample heater to avoid damage to the device.

[0021] The device of the present invention adopts a more open structure, and the sample chamber bottom tube and its supporting structure extend downward relative to the main body, which is convenient for applying external influences such as magnetic field, neutron beam, etc. at the sample position to meet the requirements of various physical property measurement environments.

[0022] The refrigerator and the refrigerator cavity in the device of the present invention are thermally coupled by crimping, and an elastic heat-conducting module is provided at the secondary cold head of the refrigerator to achieve good thermal coupling with the refrigerator cavity.

[0023] The lower extension section of the first-level heat radiation screen in the device of the present invention wraps the bottom tube of the sample chamber, thereby avoiding the influence of heat radiation of the sample under high temperature state on the device.

[0024] The device of the present invention adopts liquid helium throttling to provide a low-temperature environment, cooperates with the gas pressure control in the sample chamber and the sample heating control, realizes the low-temperature-high-temperature temperature zone segmented control of the sample temperature, controls the smooth transition between the segments, and the sample temperature change rate is adjustable. Finally, the device can realize continuous temperature change control in a wide temperature range of 2-800K, meets the needs of the current high-end physical property measurement field and fills the gap in domestic technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Attached Figure 1 It is a structural schematic diagram of a thermostat device capable of performing continuous temperature control over a wide temperature range according to the present invention;

[0026] Attached Figure 2 It is a structural schematic diagram of the elastic heat-conducting module of the present invention;

[0027] Attached Figure 3 It is the control principle diagram of the sample temperature control system of the present invention.

[0028] Among them: 1-refrigerator; 2-refrigerator mounting flange; 3-refrigerator cavity upper section; 4-refrigerator cavity adapter; 5-refrigerator cavity lower section; 6-refrigerator cavity bottom flange; 7-refrigerator cavity; 8-elastic heat conduction module; 9-heat conduction module top plate; 10-flexible heat conduction chain; 11-spring; 12-heat conduction module bottom plate; 13-vacuum cavity flange; 14-vacuum cavity cylinder; 15-first-level thermal radiation screen flange; 16-first-level thermal radiation screen cylinder; 17 —Second-stage heat radiation screen flange; 18—Second-stage heat radiation screen cylinder; 19—Refrigerator cavity liquid helium outlet; 20—Liquid helium pipeline; 21—Cryogenic valve liquid helium inlet; 22—Cryogenic valve liquid helium outlet; 23—Sample cavity liquid helium inlet; 24—Cryogenic valve; 25—Cryogenic valve control mechanism; 26—Cryogenic valve bellows; 27—Cryogenic valve normal temperature flange; 28—Cryogenic valve stem; 29—Cryogenic valve outer wall; 30—Cryogenic valve guide block; 31—Cryogenic valve primary heat sink; 32—Cryogenic valve Secondary heat sink of temperature valve; 33—valve needle of low temperature valve; 34—valve seat of low temperature valve; 35—outer cylinder of sample chamber; 36—inner cylinder of sample chamber; 37—flange of sample chamber; 38—first-stage heat sink of sample chamber; 39—lower extension of first-stage heat radiation screen; 40—bottom cylinder of sample chamber; 41—sample rod; 42—flange of sample rod; 43—rod body of sample rod; 44—heat radiation screen of rod body; 45—helium chamber; 46—circulating helium outlet; 47—static helium interface; 48—circulating pump; 49— Circulating loop charging valve; 50—circulating loop charging interface; 51—static helium charging valve; 52—static helium charging interface; 53—circulating helium inlet; 54—sample temperature sensor; 55—sample heater; 56—host computer; 57—temperature controller; 58—flow meter; 59—circulating helium pressure sensor; 60—vacuum pump; 61—liquid helium temperature sensor; 62—liquid helium heater; 63—circulating helium pipeline; 64—static helium pressure sensor. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments of the specification. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] like Figure 1-3 As shown: The present invention provides a thermostat device capable of performing continuous temperature control over a wide temperature range, the device comprising a low-temperature refrigeration system, a sample chamber component, a thermal insulation component and a sample temperature control system.

[0031] like Figure 1 , Figure 2As shown, the main components involved in the low-temperature refrigeration system include a refrigerator 1, a refrigerator cavity 7, an elastic heat conduction module 8, a liquid helium pipeline 20, a cryogenic valve 24, a cryogenic valve control mechanism 25, a circulating pump 48, a circulating loop gas charging valve 49 and a circulating helium pipeline 63. The cold head of the refrigerator 1 is inserted into the refrigerator cavity 7, and the refrigerator 1 and the refrigerator cavity 7 are thermally coupled by crimping. The refrigerator 1 is installed on the vacuum cavity flange 13 through the refrigerator mounting flange 2. The refrigerator cavity 7 includes a refrigerator cavity upper section 3 and a refrigerator cavity lower section 5. The first-level cold head of the refrigerator 1 is located in the refrigerator cavity upper section 3 and the second-level cold head of the refrigerator 1 is located in the refrigerator cavity lower section 5. The first-level cold head of the refrigerator 1 is thermally coupled with the first-level heat radiation screen flange 15 through the refrigerator cavity adapter 4 to achieve temperature synchronization; the second-level cold head of the refrigerator 1 is thermally coupled with the second-level heat radiation screen flange 17 through the refrigerator cavity bottom flange 6 to achieve temperature synchronization. An elastic heat-conducting module 8 is provided at the secondary cold head of the refrigerator 1 to realize thermal coupling with the refrigerator cavity bottom flange 6 of the refrigerator cavity 7; a refrigerator cavity liquid helium outlet 19 at the bottom of the refrigerator cavity 7 is connected with a cryogenic valve liquid helium inlet 21 on a cryogenic valve seat 34 of a cryogenic valve 24 located in the secondary heat radiation screen through a liquid helium pipeline 20 located in the secondary heat radiation screen in the heat insulation component, a cryogenic valve liquid helium outlet 22 on the cryogenic valve seat 34 is connected with a sample cavity liquid helium inlet 23 at the bottom of a sample cavity interlayer in the sample cavity component through a pipeline, and a circulating helium gas outlet 46 at the top of the sample cavity interlayer is connected with a circulating helium gas inlet 53 on the refrigerator cavity 7 through a circulating helium gas pipeline 63 with a circulating pump 48.

[0032] The above-mentioned refrigerator cavity 7, the liquid helium pipeline 20 between the refrigerator cavity liquid helium outlet 19 and the cryogenic valve liquid helium inlet 21, the inner cavity flow channel of the cryogenic valve seat 34, the pipeline between the cryogenic valve liquid helium outlet 22 and the sample cavity liquid helium inlet 23, the sample cavity interlayer in the sample cavity assembly, and the circulating helium pipeline 63 between the circulating helium outlet 46 and the circulating helium inlet 53 constitute a helium circulation system. The circulating helium flow rate control is achieved by the host computer 56 adjusting the flow rate of the circulating pump 48, and the inlet branch of the circulating helium pipeline 63 where the circulating pump 48 is located is connected to the helium storage tank, and the inlet branch is provided with a circulating loop charging valve 49 and is connected to the helium storage tank through the circulating loop charging interface 50. Since the liquid helium pipeline 20 is provided with a liquid helium temperature sensor 61 and a liquid helium heater 62 which can be controlled in linkage, and the liquid helium temperature sensor 61 and the liquid helium heater 62 are respectively connected to the temperature controller 57, the upper computer 56 performs PID closed-loop control on the liquid helium temperature sensor 61 and the liquid helium heater 62 through the temperature controller 57 to precisely control the temperature; that is, the circulating helium temperature control is achieved by adjusting the power of the liquid helium heater 62 after the secondary cold head of the refrigerator 1.

[0033] like Figure 2As shown, the elastic heat conductive module 8 is composed of a heat conductive module top plate 9, a flexible heat conductive chain 10, a spring 11, and a heat conductive module bottom plate 12. The heat conductive module top plate 9 is in direct contact with the secondary cold head of the refrigerator 1, and the heat conductive module bottom plate 12 is in direct contact with the bottom flange 6 of the refrigerator cavity. The heat conductive module bottom plate 12 and the heat conductive module top plate 9 are supported by the spring 11 and thermally coupled by the flexible heat conductive chain 10.

[0034] like Figure 1 As shown, the cryogenic valve 24 is composed of a cryogenic valve control mechanism 25, a cryogenic valve bellows 26, a cryogenic valve normal temperature flange 27, a cryogenic valve stem 28, a cryogenic valve outer wall 29, a cryogenic valve guide block 30, a cryogenic valve needle 33, a cryogenic valve seat 34 and other parts; the cryogenic valve 24 is thermally coupled to the first-level heat radiation screen flange 15 through the first-level heat sink 31 of the cryogenic valve, and is thermally coupled to the second-level heat radiation screen flange 17 through the second-level heat sink 32 of the cryogenic valve. The opening adjustment of the cryogenic valve control mechanism 25 to adjust the cryogenic valve 24 is mainly to adjust the matching clearance between the cryogenic valve needle 33 and the cryogenic valve seat 34. Since the cryogenic valve control mechanism 25 is connected to the upper computer 56 for communication, the upper computer 56 sets the stroke of the cryogenic valve needle 33 of the cryogenic valve 24 through the cryogenic valve control mechanism 25, and the cryogenic valve control mechanism 25 can feedback the stroke of the cryogenic valve needle 33 to the upper computer 56. When the opening of the cryogenic valve 24 is increased, the cryogenic valve needle 33 moves upward, so that the fit between the cryogenic valve needle 33 and the pinhole of the cryogenic valve seat 34 becomes loose and the gap increases; when the opening of the cryogenic valve 24 is reduced, the cryogenic valve needle 33 moves downward, so that the fit between the cryogenic valve needle 33 and the pinhole of the cryogenic valve seat 34 is tight and the gap decreases. The size of the above gap is positively correlated with the flow resistance of the cryogenic valve 24. By adjusting the cryogenic valve needle 33, the flow resistance of the cryogenic valve 24 can be adjusted, thereby realizing the adjustment function of the liquid helium / gas helium flow rate. For example: in a low-temperature environment, the opening of the cryogenic valve 24 is appropriately reduced, the gap is reduced, the flow resistance is increased, and the temperature of the liquid helium after throttling can be reduced.

[0035] It should be noted that the cryogenic valve 24 can be replaced by a multi-channel pipeline with adjustable flow resistance.

[0036] When the low-temperature refrigeration system is in operation, helium with a slight positive pressure enters the refrigerator cavity 7 from the circulating helium inlet 53, and sequentially contacts with the primary cold head and the secondary cold head of the refrigerator 1 for heat exchange and liquefaction, and the liquid helium enters the liquid helium inlet 21 of the cryogenic valve from the liquid helium outlet 19 of the refrigerator cavity through the liquid helium pipeline 20; the liquid helium is decompressed and expanded through the cryogenic valve 24 to become a gas-liquid mixed helium flow with a lower temperature, and then flows out of the cryogenic valve 24 from the sample cavity liquid helium inlet 23 to enter the sample cavity interlayer between the sample cavity outer tube 35 and the sample cavity inner tube 36, and exchanges heat with the sample cavity from bottom to top, and the heated helium is extracted by the circulating pump 48 from the circulating helium outlet 46 at the upper end of the sample cavity interlayer, and it is determined whether to pressurize it according to the actual situation, and then it is re-delivered to the circulating helium inlet 53 on the refrigerator cavity 7 through the circulating helium pipeline 63, and a refrigeration cycle is completed. In addition, after the device has been running for a long time, the amount of liquid helium increases and the helium pressure decreases. At this time, the circulation loop charging valve 49 is opened to replenish helium into the circulation loop from the circulation loop charging interface 50 to maintain the normal operation of the low-temperature refrigeration system.

[0037] In addition, a flow meter 58 for monitoring the flow rate of circulating helium and a circulating helium pressure sensor 59 for monitoring the pressure of circulating helium are also provided on the circulating helium pipeline 63. The flow meter 58 and the circulating helium pressure sensor 59 are respectively connected to the host computer 56 to feedback the flow rate and pressure of circulating helium; the flow meter 58 is located on the rear side of the outlet of the circulating pump 48 on the circulating helium pipeline 63, and the circulating helium pressure sensor 59 is located on the front side of the inlet of the circulating pump 48 on the circulating helium pipeline 63.

[0038] like Figure 1As shown, the thermal insulation component includes a vacuum cavity, a primary thermal radiation screen and a secondary thermal radiation screen, wherein the vacuum cavity is composed of a vacuum cavity flange 13 and a vacuum cavity cylinder 14, and the bottom of the vacuum cavity cylinder 14 is partially convex; the primary thermal radiation screen composed of a primary thermal radiation screen cylinder 16 and a primary thermal radiation screen flange 15 is suspended in the vacuum cavity, and the primary thermal radiation screen is provided with a primary thermal radiation screen lower extension section 39 extending from the primary thermal radiation screen flange 15 downward through the bottom of the primary thermal radiation screen cylinder 16 and extending to the lower convex part of the vacuum cavity cylinder 14, and the portion of the primary thermal radiation screen lower extension section 39 extending out of the bottom of the vacuum cavity cylinder 14 and the lower convex part of the vacuum cavity cylinder 14 constitute a thermal insulation sinking cavity; the secondary thermal radiation screen composed of a secondary thermal radiation screen cylinder 18 and a secondary thermal radiation screen flange 17 is suspended in the primary thermal radiation screen. The vacuum chamber formed by connecting the vacuum chamber flange 13 with the vacuum chamber barrel 14 is evacuated by a vacuum pump 60 to reduce the heat leakage caused by gas heat conduction between the inside of the device and the external environment. The heat radiation screen barrel and its flange are made of high thermal conductivity materials and are treated to reduce the surface emissivity. In this way, the radiation heat leakage process is isolated and the radiation heat leakage of the system is greatly reduced; the lower extension section 39 of the first-level heat radiation screen wraps the sample chamber bottom barrel 40 to prevent the heat radiation of the sample in the high temperature state from affecting the main body of the device.

[0039] On this basis, by setting temperature monitoring points on the primary thermal radiation screen and the secondary thermal radiation screen respectively, the temperature sensors set at the temperature monitoring points are respectively connected to the temperature controller 57 to feed back the real-time monitored temperature to the host computer 56; since the vacuum pump 60 configured in the vacuum chamber is connected to the host computer 56, the host computer 56 can control the vacuum degree in the vacuum chamber through the vacuum pump 60.

[0040] The sample chamber assembly includes, from top to bottom, a sample rod 41, a sample rod flange 42, a sample chamber flange 37, a sample chamber outer tube 35, a sample chamber inner tube 36, a sample rod body 43, a rod body heat radiation screen 44, a helium chamber 45, and a sample chamber bottom tube 40. The sample chamber assembly is thermally coupled to the primary heat radiation screen flange 15 through the sample chamber primary heat sink 38; the sample rod body 43 of the sample rod 41 is inserted into the sample chamber inner tube 36 and the sample chamber bottom tube 40, and the sample rod 41 is fixed to the sample chamber flange 37 through the sample rod flange 42; a plurality of parallel heat radiation screens 44 are provided on the sample rod body 43, which can effectively reduce the radiation heat leakage at the sample; because the sample chamber bottom tube 40 and its supporting structure extend downward relative to the main body, it is convenient to apply external influences, such as magnetic field, neutron beam, etc., to the sample position. The sample cavity outer tube 36 and the sample cavity inner tube 35 form a sample cavity interlayer, and the two ends of the sample cavity interlayer are respectively connected to the sample cavity liquid helium inlet 23 and the circulating helium outlet 46; the low-temperature helium gas behind the low-temperature valve 24 flows through the sample cavity interlayer and cools the sample cavity inner tube 36. Since the sample mainly conducts heat through the static helium, the sample is cooled by the heat exchange between the static helium filled in the helium cavity 45 and the sample cavity inner tube 36. The helium after the heat exchange enters the circulating helium pipeline 63 from the circulating helium outlet 46 at the upper end of the sample cavity interlayer.

[0041] In addition, since the sample rod body 43 for placing the sample is provided with a sample temperature sensor 54 and a sample heater 55, the sample temperature sensor 54 and the sample heater 55 are respectively connected to the temperature controller 57 in the sample temperature control system, and the temperature controller 57 is connected to the host computer 56 through a line, and the host computer 56 performs PID closed-loop control on the sample temperature sensor 54 and the sample heater 55 through the temperature controller 57. At the same time, a static helium pressure sensor 64 for monitoring the static helium pressure is provided on the static helium pipeline located at the top of the sample cavity inner cylinder 36 and connected to the static helium interface 47 for controlling the static helium pressure. The static helium pressure sensor 64 is connected to the host computer 56 to feedback the pressure of the static helium; when the static helium pressure in the static helium pipeline needs to be regulated, the static helium pressure in the helium cavity 45 can be adjusted through the static helium inflation valve 51 and the static helium inflation interface 52, thereby adjusting the heat exchange between the sample and the outside.

[0042] The sample temperature control system provided by the present invention can perform low-temperature-high-temperature zone segmented temperature control. Among them, 2-300K is the low-temperature zone, and 300-800K is the high-temperature zone, and the two temperature zones adopt different temperature control modes. The temperature control system is composed of a host computer 56, a temperature controller 57, a low-temperature valve control mechanism 25, a flow meter 58, a circulating helium pressure sensor 59, a vacuum pump 60, a static helium pressure sensor 64, and a circulating pump 48, and the temperature controller 57 adopts PID closed-loop control of the sample temperature sensor 54 and the sample heater 55, the liquid helium temperature sensor 61 and the liquid helium heater 62. The host computer 56 has an overview control and sets the target value according to the feedback data; the manipulated variables of the sample temperature control system include the opening of the low-temperature valve 24, the flow and temperature of the circulating helium, the circulating helium pressure and the static helium pressure, and the power of the sample heater 55 on the sample rod body 43. The low-temperature-high-temperature temperature zone is further divided into many small temperature zones. Different control parameters are set for each small temperature zone. With the overall control of the host computer, a smooth transition between temperature zones can be achieved, and finally the continuous temperature change of the device can be achieved with adjustable sample temperature change rate.

[0043] When the device of the present invention performs low temperature zone control of 2-300K, firstly, the static helium charging valve 51 on the static helium pipeline and the static helium charging interface 52 connected to the static helium pipeline are used to control the air pressure in the helium cavity 45 storing the sample to be 200-500Pa, so as to ensure that the static helium has good thermal conductivity; secondly, the opening of the cryogenic valve 24 is reduced by manipulating the cryogenic valve control mechanism 25, so as to ensure that the liquid helium in the liquid helium pipeline 20 can be throttled and cooled sufficiently; the throttled low temperature circulating helium cools the inner cylinder 36 of the sample cavity, and cools the sample by heat conduction of the static helium; a sample temperature sensor 54 and a sample heater 55 are provided at the sample, which are controlled by a PID closed loop. When the sample temperature is lower than the set value, the sample heater 55 will heat the sample until the temperature reaches the set value.

[0044] When the device of the present invention performs high temperature zone control of 300-800K, the sample is heated by the sample heater 55 controlled by PID to reach the set high temperature zone temperature. In order to prevent the main part of the device from being damaged by the high temperature of the sample, it is necessary to insulate the high temperature sample and cool the sample cavity. First, the static helium gas filling valve 51 on the static helium pipeline and the static helium gas filling interface 52 connected to the static helium pipeline are used to control the air pressure in the helium cavity 45 where the sample is stored to be below 1Pa. At this time, the static helium is in a molecular flow state, ensuring that the heat that the high temperature sample can conduct through the static helium is extremely small. The total heat leakage calculated by simulation is less than 15W, which is basically consistent with the actual test; secondly, by controlling the cryogenic valve control mechanism 25, the opening of the cryogenic valve 24 is increased, and the helium flow resistance is reduced. The helium flow rate only needs about 2 standard liters / minute to effectively cool the sample cavity wall. The system controls the sample chamber wall temperature below room temperature by adjusting the temperature and flow of circulating helium. The circulating helium flow control is achieved by adjusting the flow of the circulating pump 48. If the helium amount is insufficient, it is supplemented through the circulating loop charging interface 50. The circulating helium temperature control is achieved by adjusting the power of the liquid helium heater 62 after the secondary cold head of the refrigerator 1, and the liquid helium heater 62 and the liquid helium temperature sensor 61 adopt PID closed-loop control to accurately control the temperature.

[0045] It should be noted that, when the temperature is 300K, the device of the present invention can select either a low temperature zone control mode or a high temperature zone control mode.

[0046] When the sample temperature control system of the present invention performs low temperature zone control, the static helium pressure in the sample cavity is controlled within the range of 200-500Pa, the opening of the cryogenic valve 24 is relatively small, the refrigerator 1 liquefies the circulating helium, the liquid helium is throttled to obtain a lower temperature, and the static helium in the sample cavity is used as a heat transfer medium to cool the sample. This process works in conjunction with the sample heater 55 controlled by PID closed loop, and finally achieves precise temperature control of the sample. When the sample temperature control system performs high temperature zone control, the static helium pressure in the sample cavity is controlled below 1Pa, the opening of the cryogenic valve 24 is relatively large, the static helium in the sample cavity is in a molecular flow state, and the heat transfer between the sample cavity and the sample is extremely small; the sample is heated by the sample heater 55, and the sample heater 55 adopts PID closed loop control to achieve precise temperature control; in order to prevent the sample cavity wall from overheating and damaging the device, the system controls the sample cavity wall temperature by adjusting the temperature and flow of the circulating helium that exchanges heat with it. The above-mentioned sample temperature control system has an emergency processing function. When the temperature feedback from the temperature controller 57 exceeds the safe area, the output of the sample heater 55 is immediately cut off; that is, except for the sample position, once the remaining temperature monitoring points of the device exceed the normal temperature to a certain extent, the sample temperature control system will alarm and cut off the power supply of the sample heater 55 to avoid damage to the device.

[0047] Specifically, when the device of the present invention performs high-temperature zone control, the circulating helium flow control is achieved by adjusting the flow of the circulating pump 48, and the air inlet branch of the circulating helium pipeline 63 where the circulating pump 48 is located is connected to the helium storage tank; the circulating helium temperature control is achieved by adjusting the power of the liquid helium heater 62 after the secondary cold head of the refrigerator 1, and the liquid helium heater 62 and the liquid helium temperature sensor 61 adopt PID closed-loop control to accurately control the temperature.

[0048] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention; any technology not involved in the present invention can be realized by existing technologies.

Claims

1. A thermostat device capable of performing continuous temperature control over a wide temperature range, characterized in that: The device comprises a low-temperature refrigeration system, a sample chamber component, a heat insulation component and a sample temperature control system. A sample temperature sensor (54) and a sample heater (55) are arranged on a sample rod body (43) for placing a sample in the sample chamber component. The sample temperature sensor (54) and the sample heater (55) are respectively connected to a temperature controller (57) in the sample temperature control system. The temperature controller (57) is connected to a host computer (56) via a line. The host computer (56) performs PID closed-loop control on the sample temperature sensor (54) and the sample heater (55) via the temperature controller (57). A static helium pressure sensor (64) for monitoring the static helium pressure is arranged on a static helium pipeline connected to a static helium interface (47) for controlling the static helium pressure in the sample chamber component. The static helium pressure sensor (64) is connected to the host computer (56) to feedback the pressure of the static helium. The cryogenic valve (24) in the cryogenic refrigeration system is provided with a cryogenic valve control mechanism (25) which is communicatively connected to a host computer (56); the host computer (56) sets the stroke of a cryogenic valve needle (33) of the cryogenic valve (24) through the cryogenic valve control mechanism (25); and the cryogenic valve control mechanism (25) can feed back the stroke of the cryogenic valve needle (33) to the host computer (56); A liquid helium temperature sensor (61) and a liquid helium heater (62) capable of linkage control are arranged on the liquid helium pipeline (20) in the cryogenic refrigeration system; the liquid helium temperature sensor (61) and the liquid helium heater (62) are respectively connected to a temperature controller (57); and the host computer (56) performs PID closed-loop control on the liquid helium temperature sensor (61) and the liquid helium heater (62) through the temperature controller (57); A flow meter (58) for monitoring the flow rate of the circulating helium and a circulating helium pressure sensor (59) for monitoring the pressure of the circulating helium are provided on the circulating helium pipeline (63) in the low-temperature refrigeration system. The flow meter (58) and the circulating helium pressure sensor (59) are respectively connected to the host computer (56) to feed back the flow rate and pressure of the circulating helium. The flow meter (58) is located at the rear side of the gas outlet of the circulating pump (48) on the circulating helium pipeline (63); and the circulating helium pressure sensor (59) is located at the front side of the gas inlet of the circulating pump (48) on the circulating helium pipeline (63). Temperature monitoring points are respectively arranged on the primary heat radiation screen and the secondary heat radiation screen in the thermal insulation component, and the temperature sensors arranged at the temperature monitoring points are respectively connected to the temperature controller (57) to feed back the real-time monitored temperature to the host computer (56); the vacuum cavity in the thermal insulation component is provided with a vacuum pump (60), and the vacuum pump (60) is connected to the host computer (56), so that the host computer (56) can control the vacuum degree in the vacuum cavity through the vacuum pump (60).

2. The thermostat device capable of performing continuous temperature control over a wide temperature range according to claim 1, characterized in that: The local downward protrusion of the thermal insulation component forms a thermal insulation sinking cavity to accommodate the sample cavity bottom cylinder (40) in the sample cavity component, and the sample rod body (43) in the sample cavity component extends into the sample cavity bottom cylinder (40).

3. The thermostat device capable of performing continuous temperature control over a wide temperature range according to any one of claims 1-2, characterized in that: The thermal insulation component comprises a vacuum cavity, a primary heat radiation screen and a secondary heat radiation screen, wherein the vacuum cavity is composed of a vacuum cavity flange (13) and a vacuum cavity cylinder (14), and the bottom of the vacuum cavity cylinder (14) is partially convex; the primary heat radiation screen, which is composed of a primary heat radiation screen cylinder (16) and a primary heat radiation screen flange (15), is suspended in the vacuum cavity, and the primary heat radiation screen is provided with a primary heat radiation screen lower extension section (39) extending from the primary heat radiation screen flange (15) downward through the bottom of the primary heat radiation screen cylinder (16) and extending to the lower convex part of the vacuum cavity cylinder (14), and the portion of the primary heat radiation screen lower extension section (39) extending out of the bottom of the vacuum cavity cylinder (14) and the lower convex part of the vacuum cavity cylinder (14) constitute a thermal insulation sinking cavity; the secondary heat radiation screen, which is composed of a secondary heat radiation screen cylinder (18) and a secondary heat radiation screen flange (17), is suspended in the primary heat radiation screen.

4. The thermostat device capable of performing continuous temperature control over a wide temperature range according to any one of claims 1-2, characterized in that: The cryogenic refrigeration system comprises a refrigerator (1), a refrigerator cavity (7), a cryogenic valve (24) controlled by a cryogenic valve control mechanism (25), and a helium circulation system. The cold head of the refrigerator (1) is inserted into the refrigerator cavity (7), and the refrigerator (1) and the refrigerator cavity (7) are thermally coupled by crimping. An elastic heat conductive module (8) is provided at the secondary cold head of the refrigerator (1) to achieve thermal coupling with a refrigerator cavity bottom flange (6) of the refrigerator cavity (7). The refrigerator cavity liquid helium outlet (19) at the bottom of the refrigerator cavity (7) is connected to a cryogenic valve liquid helium inlet (21) on a cryogenic valve seat (34) of the cryogenic valve (24) located in the secondary heat radiation screen through a liquid helium pipeline (20) located in a secondary heat radiation screen in a heat insulation component. The cryogenic valve seat (34) is provided with a liquid helium outlet (19) at the bottom of the refrigerator cavity (7). The cryogenic valve liquid helium outlet (22) is connected to the sample chamber liquid helium inlet (23) at the bottom of the sample chamber sandwich in the sample chamber assembly through a pipeline, and the circulating helium outlet (46) at the top of the sample chamber sandwich is connected to the circulating helium inlet (53) on the refrigerator chamber (7) through a circulating helium pipeline (63) with a circulating pump (48). The refrigerator chamber (7), the liquid helium pipeline (20) between the refrigerator chamber liquid helium outlet (19) and the cryogenic valve liquid helium inlet (21), the inner cavity flow channel of the cryogenic valve seat (34), the pipeline between the cryogenic valve liquid helium outlet (22) and the sample chamber liquid helium inlet (23), the sample chamber sandwich in the sample chamber assembly, and the circulating helium pipeline (63) between the circulating helium outlet (46) and the circulating helium inlet (53) constitute a helium circulation system.

5. The thermostat device capable of performing continuous temperature control over a wide temperature range according to claim 4, characterized in that: The elastic heat-conducting module (8) is composed of a heat-conducting module top plate (9), a flexible heat-conducting chain (10), a spring (11), and a heat-conducting module bottom plate (12); the heat-conducting module top plate (9) is in direct contact with the secondary cold head of the refrigerator (1), and the heat-conducting module bottom plate (12) is in direct contact with the bottom flange (6) of the refrigerator cavity; the heat-conducting module bottom plate (12) and the heat-conducting module top plate (9) are supported by the spring (11) and are thermally coupled by the flexible heat-conducting chain (10).

6. The thermostat device capable of performing continuous temperature control over a wide temperature range according to any one of claims 1-2, characterized in that: The sample chamber assembly comprises a sample chamber outer tube (35), a sample chamber inner tube (36), a sample chamber bottom tube (40) as an extension of the sample chamber inner tube (36), a sample chamber flange (37), a sample rod (41), and a sample rod flange (42); a sample rod body (43) of the sample rod (41) is inserted into the sample chamber inner tube (36) and the sample chamber bottom tube (40), and the sample rod (41) is fixed to the sample chamber flange (37) via the sample rod flange (42); rod body heat radiation shields (44) are evenly distributed on the sample rod body (43); a sample chamber sandwich is formed between the sample chamber outer tube (35) and the sample chamber inner tube (36); a low-temperature helium flow after the low-temperature valve (24) flows through the sample chamber sandwich to cool a helium chamber (45) formed by the sample chamber inner tube (36) and the sample chamber bottom tube (40), and enters a circulating helium pipeline (63) from a circulating helium outlet (46) at the upper end of the sample chamber sandwich.

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