A liquid nitrogen thermostat

Abstract

The application discloses a kind of liquid nitrogen constant-temperature calibrators, including dewar jar, liquid nitrogen is filled in dewar jar, the top of dewar jar is equipped with filling opening, filling opening is fixedly connected with cover, the middle part of cover is formed into the installation cavity of inward recess, installation cavity is equipped with thermostat cylinder, thermostat cylinder is respectively connected with temperature control piece, standard piece and determination piece, the lower end of thermostat cylinder passes through filling opening and extends to liquid nitrogen, the upper end of thermostat cylinder is detachably connected cover by sealing assembly;The sealing assembly includes lower sealing block in the bottom of installation cavity, the inner side of lower sealing block is attached thermostat cylinder by inclined pressure surface, the outer side of lower sealing block is equipped with the limiting surface of cooperation cover, the top of lower sealing block is screw-connected with upper sealing block by annular part, the lower end of upper sealing block is equipped with step part, the lower end of step part passes through annular part and is attached the top surface of thermostat cylinder.The application has the characteristics of good temperature control effect, high detection accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to a constant temperature detector, in particular to a liquid nitrogen constant temperature detector. BACKGROUND

[0002] The constant temperature detector is a detection tool for measuring the detection accuracy of a temperature sensor, which detects the temperature sensor to be tested and a standard temperature sensor in the same temperature environment, and then compares the measured temperature values of the two to determine the detection accuracy and detection precision of the test piece. The existing constant temperature detector mainly consists of a test tank and a temperature control part. The surface of the test tank is coated with thermal insulation material to avoid interference of the external environment temperature on the test temperature in the test tank. The temperature control part is used to heat or cool the internal temperature of the test tank to obtain a specified test temperature, so as to realize the test of the test piece at any temperature.

[0003] However, the structure has the following defects. On the one hand, although the test tank reduces interference by wrapping thermal insulation material, the external environment still affects the internal temperature of the test tank. The detection precision of the temperature sensor is generally in the range of ±0.1-0.2℃, so that once the temperature in the test tank is slightly disturbed by the external environment, the temperature difference in different areas is easy to occur, which further causes the decrease of the detection accuracy. On the other hand, only relying on the temperature control part to heat or cool the test tank, the temperature control part stops working when the test tank reaches the specified temperature value, and restarts to control the temperature when the temperature change in the test tank is detected. This makes the temperature in the test tank continuously change in a certain temperature range instead of keeping at a constant temperature value, which makes the detection value of the temperature sensor fluctuate, and the temperature sensor cannot be continuously detected in a constant temperature environment, which reduces the detection effect of the temperature sensor.

[0004] Therefore, the existing constant temperature detector has the problems of poor temperature control effect and low detection accuracy. SUMMARY

[0005] The present application relates to a constant temperature detector, in particular to a liquid nitrogen constant temperature detector.

[0006] The technical scheme of the present application: a liquid nitrogen constant temperature detector, comprising a dewar flask, the dewar flask is filled with liquid nitrogen, the top of the dewar flask is provided with a pouring port, the pouring port is fixedly connected with a cover, the middle part of the cover is formed with an inwardly recessed mounting cavity, a constant temperature cylinder is arranged in the mounting cavity, the constant temperature cylinder is respectively connected with a temperature control part, a standard part and a measuring part, the lower end of the constant temperature cylinder penetrates through the pouring port and extends into the liquid nitrogen, and the upper end of the constant temperature cylinder is detachably connected with the cover through a sealing assembly; the sealing assembly comprises a lower sealing block located at the bottom of the mounting cavity, the inner side of the lower sealing block is matched with the constant temperature cylinder through an inclined pressure receiving surface, the outer side of the lower sealing block is provided with a limiting surface matched with the cover, the top of the lower sealing block is threadedly connected with an upper sealing block through an annular portion, the lower end of the upper sealing block is provided with a stepped portion, and the lower end of the stepped portion penetrates through the annular portion and is matched with the top surface of the constant temperature cylinder.

[0007] In the foregoing liquid nitrogen constant temperature detector, the bottom of the lower sealing block is provided with a plurality of extrusion portions around, the adjacent extrusion portions are separated from each other through first grooves, and the pressure receiving surface and the limiting surface are respectively located on the inner side and the outer side of the extrusion portions.

[0008] In the foregoing liquid nitrogen constant temperature detector, the outer side of the constant temperature cylinder is provided with an extrusion surface matched with the pressure receiving surface.

[0009] In the foregoing liquid nitrogen constant temperature detector, the bottom of the cover is annularly provided with a plurality of limiting plates, and the plurality of limiting plates are respectively located in the first grooves between the extrusion portions.

[0010] In the foregoing liquid nitrogen constant temperature detector, the constant temperature cylinder comprises an outer cylinder and an inner cylinder, a vacuum area is formed between the outer cylinder and the inner cylinder, the top of the outer cylinder and the inner cylinder is connected with each other through a plurality of sleeves, the temperature control part, the standard part and the measuring part are arranged in the plurality of sleeves respectively, the lower end of the temperature control part, the standard part and the measuring part extends to the inner cylinder, and the upper end of the temperature control part, the standard part and the measuring part extends to the outer side of the sealing assembly through the constant temperature cylinder in sequence.

[0011] In the foregoing liquid nitrogen constant temperature detector, a plurality of mounting holes matched with the temperature control part, the standard part and the measuring part are arranged on the upper sealing block, a supporting sleeve is connected in the mounting hole, and the lower end of the supporting sleeve penetrates through the mounting hole and extends to the sleeve.

[0012] In the foregoing liquid nitrogen constant temperature detector, the top of the supporting sleeve is provided with a locking part for fixing the temperature control part, the standard part or the measuring part.

[0013] In the foregoing liquid nitrogen constant temperature detector, a gap is left between the side wall of the cover and the inner wall of the pouring port, and a plurality of openings for discharging nitrogen gas are arranged on the top of the cover.

[0014] Compared with the prior art, the present application has the following characteristics:

[0015] (1) The present application can provide a stable external environment for the constant temperature cylinder on the inner side by filling liquid nitrogen in the Dewar flask, and the liquid nitrogen at-196 DEG C continuously cools the constant temperature cylinder during the detection process, while the temperature control member in the constant temperature cylinder warms up, so that the temperature in the constant temperature cylinder is controlled to remain at a relatively constant temperature value through the cooperation of the two, the temperature accuracy of the measuring element in the range of-80 DEG C to-196 DEG C is detected, and the up and down fluctuation of the temperature in the constant temperature cylinder during the detection process is reduced; on this basis, the cooling efficiency of the liquid nitrogen to the inner cylinder is also reduced by forming a vacuum zone between the outer cylinder and the inner cylinder, so that the temperature of the inner cylinder is slowly lowered under the action of the refrigerant, that is, the temperature change rate of the inner cylinder is reduced, the temperature adjustment and control of the inner cylinder by the temperature control member are facilitated, and the temperature control effect and the detection accuracy of the measuring element of the present application are further improved;

[0016] (2) The connecting structure of the constant temperature cylinder, the cover body and the sealing assembly is limited, so that the constant temperature cylinder can be directly inserted into the Dewar flask from the pouring opening during installation, and the constant temperature cylinder is locked through the cooperation of the upper sealing block and the lower sealing block, so that the disassembly and fixation of the constant temperature cylinder are realized, and the assembly of the operating personnel is facilitated; the upper sealing block and the lower sealing block can also separate the top of the constant temperature cylinder from the external environment after being connected, so as to play a heat preservation effect and further improve the temperature stability of the inner cylinder;

[0017] (3) Through the structure cooperation of the sleeve, the mounting hole and the support sleeve, the constant temperature cylinder can also be connected with the upper sealing block through the insertion of the support sleeve after being extruded and fixed, and under this structure, the friction force between the constant temperature cylinder and the lower sealing block can limit the rotation of the upper sealing block, that is, the upper sealing block is prevented from being loosened and rotated out, and the fixing effect of the sealing assembly and the constant temperature cylinder after installation is further improved; on the other hand, through the limitation of the above structure, the cover body does not need to be provided with a structure for fixing the sealing assembly and the constant temperature cylinder, so that the processing difficulty of the cover body is effectively reduced;

[0018] Therefore, the present application has the characteristics of good temperature control effect and high detection accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic view of the present application;

[0020] Figure 2 is an enlarged view of A of Figure 1 ;

[0021] Figure 3 is a top view of the lower sealing block;

[0022] Figure 4 is an enlarged view of B of Figure 1 ;

[0023] The marks in the drawings are: 1-dewar flask, 2-cover, 3-mounting cavity, 4-thermostatic cylinder, 5-temperature control piece, 6-standard piece, 7-measuring piece, 8-lower sealing block, 9-pressing surface, 10-limiting surface, 11-annular part, 12-upper sealing block, 13-first groove, 14-second groove, 15-limiting plate, 16-sleeve, 17-mounting hole, 18-supporting sleeve, 801-extrusion part, 121-step part. DETAILED DESCRIPTION

[0024] The application will be further described below in conjunction with the drawings and examples, but not as the basis for limiting the application.

[0025] Example. A liquid nitrogen constant temperature detector is constituted as shown in Figure 1 The liquid nitrogen constant temperature detector comprises a dewar flask 1, the dewar flask 1 is provided with a liquid nitrogen filling port on one side, the dewar flask 1 is filled with liquid nitrogen, the top of the dewar flask 1 is provided with a filling port, the filling port is fixedly connected with a cover 2, the middle part of the cover 2 forms a mounting cavity 3 which is concave inward, a thermostatic cylinder 4 is arranged in the mounting cavity 3, the thermostatic cylinder 4 is respectively connected with a temperature control piece 5, a standard piece 6 and a measuring piece 7, the lower end of the thermostatic cylinder 4 extends into the liquid nitrogen through the filling port, and the upper end of the thermostatic cylinder 4 is detachably connected with the cover 2 through a sealing assembly; the sealing assembly comprises a lower sealing block 8 arranged at the bottom of the mounting cavity 3, the inner side of the lower sealing block 8 is attached to the thermostatic cylinder 4 through an inclined pressing surface 9, the outer side of the lower sealing block 8 is provided with a limiting surface 10 matched with the cover 2, a flexible sealing ring can be arranged on the limiting surface 10, the top of the lower sealing block 8 is threadedly connected with an upper sealing block 12 through an annular part 11, the outer part of the upper sealing block 12 is attached to the sidewall of the cover 2, and the lower end of the upper sealing block 12 is provided with a step part 121, the lower end of the step part 121 passes through the annular part 11 and is attached to the top surface of the thermostatic cylinder 4.

[0026] The bottom of the lower sealing block 8 is provided with a plurality of extrusion parts 801, the adjacent extrusion parts 801 are separated from each other through a first groove 13, the pressing surface 9 and the limiting surface 10 are respectively located on the inner and outer sides of the extrusion parts 801, and a second groove 14 for the deformation and opening of the extrusion parts 801 can be arranged between the extrusion parts 801 and the annular part 11.

[0027] The outer side of the thermostatic cylinder 4 is provided with an extrusion surface matched with the pressing surface 9.

[0028] The bottom of the cover 2 is annularly provided with a plurality of limiting plates 15, and the plurality of limiting plates 15 are respectively arranged in the first grooves 13 between the extrusion parts 801.

[0029] The constant temperature cylinder 4 comprises an outer cylinder and an inner cylinder, a vacuum area is formed between the outer cylinder and the inner cylinder, the top of the outer cylinder and the inner cylinder are connected with each other through a plurality of sleeves 16, the temperature control element 5, the standard element 6 and the determination element 7 are arranged in the plurality of sleeves 16 respectively, wherein the temperature control element 5 can be a heating pipe, the standard element 6 is a required temperature sensor, the determination element 7 is a temperature sensor for determining the detection accuracy, the lower ends of the temperature control element 5, the standard element 6 and the determination element 7 extend to the inner cylinder, and the upper ends of the temperature control element 5, the standard element 6 and the determination element 7 extend to the outside of the sealing assembly through the constant temperature cylinder 4 in sequence.

[0030] A plurality of mounting holes 17 for matching the temperature control element 5, the standard element 6 and the determination element 7 are arranged on the upper sealing block 12, a supporting sleeve 18 is connected in the mounting hole 17, the lower end of the supporting sleeve 18 extends to the sleeve 16 through the mounting hole 17, and the supporting sleeve 18 is fixed on the mounting hole 17 in a threaded connection or interference fit plug-in mode, so as to prevent it from falling out during use.

[0031] A locking element for fixing the temperature control element 5, the standard element 6 or the determination element 7 is arranged on the top of the supporting sleeve 18, and the locking element can be a flexible rubber sleeve, a conical nut or other conventional locking structures for height limiting of a cylindrical structure.

[0032] A gap is left between the side wall of the cover body 2 and the inner wall of the pouring opening, and a plurality of openings for discharging nitrogen are arranged on the top of the cover body 2.

[0033] The working principle of the application is as follows: when the application is installed, the operator first places the lower sealing block 8 at the bottom of the installation cavity 3 and makes the first groove 13 and the limiting plate 15 be buckled with each other, then inserts the constant temperature cylinder 4 after vacuumizing into the Dewar jar 1 through the installation cavity 3, and supports the constant temperature cylinder 4 by using the cooperation of the pressure receiving surface 9 and the extrusion surface. After the constant temperature cylinder 4 is inserted, the operator rotates the upper sealing block 12 into the annular part 11 at the upper end of the lower sealing block 8, and makes the upper sealing block 12 apply a downward extrusion force to the constant temperature cylinder 4 after being rotated, so that the constant temperature cylinder 4 is extruded outward by the cooperation of the pressure receiving surface 9 and the extrusion surface to the extrusion part 801 around, and the extrusion part 801 is in frictional limiting with the side wall of the cover body 2 under the extrusion.

[0034] After the upper sealing block 12 is screwed in, the operator aligns the sleeves 16 and the mounting holes 17 with each other, and then inserts the supporting sleeves 18, so that the supporting sleeves 18 can define the circumferential positions of the upper sealing block 12 and the mounting cavity 3 after being inserted; in this state, the upper sealing block 12 needs to overcome the friction between the constant-temperature cylinder 4 and the lower sealing block 8 to limit the constant-temperature cylinder 7 and the sealing assembly, preventing them from loosening and falling out of the cover 2. During subsequent disassembly, the operator only needs to pull out the supporting sleeves 18, and then can individually screw out the upper sealing block 12, and then directly pull out the constant-temperature cylinder 4, which is convenient for the operator to disassemble later.

[0035] In use, the liquid nitrogen around the constant-temperature cylinder 4 can cool the constant-temperature cylinder 4, and the temperature control member 5 in the constant-temperature cylinder 4 can heat it, so that the temperature in the inner cylinder can be maintained within a certain temperature value under the cooperation of the two, thereby realizing the temperature accuracy detection of the measuring member 7 in the range of-80℃ to-196℃. At this time, the measuring member 7 to be detected is inserted into the constant-temperature cylinder 4 through the supporting sleeve 18, and the temperature of the inner cylinder is detected, and the detection result of the measuring member 7 is compared with the detection result of the standard member 6, so as to judge whether the measuring member 7 has detection error.

Claims

1. A liquid nitrogen thermostat calibrator characterized by: The utility model provides a temperature control device for liquid nitrogen, which comprises a Dewar flask (1) filled with liquid nitrogen, a pouring opening provided at the top of the Dewar flask (1), a cover (2) fixedly connected to the pouring opening, an installation cavity (3) formed in the middle of the cover (2) and concave inward, a thermostat cylinder (4) provided in the installation cavity (3), a temperature control component (5), a standard component (6) and a measuring component (7) connected to the thermostat cylinder (4) respectively, the lower end of the thermostat cylinder (4) extending into the liquid nitrogen through the pouring opening, and the upper end of the thermostat cylinder (4) being detachably connected to the cover (2) through a sealing assembly. The sealing assembly comprises a lower sealing block (8) provided at the bottom of the installation cavity (3), an inclined pressure surface (9) on the inner side of the lower sealing block (8) abutting against the thermostat cylinder (4), a limiting surface (10) on the outer side of the lower sealing block (8) matching the cover (2), an upper sealing block (12) threadedly connected to the top of the lower sealing block (8) through an annular portion (11), a stepped portion (121) provided at the lower end of the upper sealing block (12), and the lower end of the stepped portion (121) extending through the annular portion (11) and abutting against the top surface of the thermostat cylinder (4). A plurality of extrusion portions (801) are provided around the bottom of the lower sealing block (8), and the adjacent extrusion portions (801) are separated from each other by a first groove (13). An extrusion surface matching the pressure surface (9) is provided on the outer side of the thermostat cylinder (4). The thermostat cylinder (4) comprises an outer cylinder and an inner cylinder, and a vacuum zone is formed between the outer cylinder and the inner cylinder, the top of the outer cylinder and the inner cylinder being connected to each other by a plurality of sleeves (16), the temperature control component (5), the standard component (6) and the measuring component (7) being arranged in the plurality of sleeves (16) respectively, the lower end of each of the temperature control component (5), the standard component (6) and the measuring component (7) extending into the inner cylinder, and the upper end of each of the temperature control component (5), the standard component (6) and the measuring component (7) extending to the outer side of the sealing assembly through the thermostat cylinder (4) in sequence. A plurality of mounting holes (17) matching the temperature control component (5), the standard component (6) and the measuring component (7) are provided on the upper sealing block (12), and a support sleeve (18) is connected in each of the mounting holes (17), the lower end of the support sleeve (18) extending into the sleeve (16) through the mounting hole (17). A plurality of limiting plates (15) are annularly distributed on the bottom of the cover (2), and each of the limiting plates (15) is arranged in the first groove (13) between the extrusion portions (801). A locking component for fixing the temperature control component (5), the standard component (6) or the measuring component (7) is provided on the top of the support sleeve (18). A gap is left between the side wall of the cover (2) and the inner wall of the pouring opening, and a plurality of openings for discharging nitrogen are provided on the top of the cover (2).

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