Immersion system for dynamic calibration of thermocouple

Abstract

The utility model discloses an immersion type system for dynamic calibration of a thermocouple. The immersion type system integrates a high-temperature oil tank, a medium tank, an electric push rod, a connector, a laser speed measurement system, a control system, a rack, a temperature shielding structure and the like. The high-temperature oil groove provides a stable heat source, and dynamic calibration of the thermocouple under different media is realized through cooperation of the calibration hole and the medium groove. The electric push rod and the control system work cooperatively to accurately control the immersion depth, speed and posture of the thermocouple. The medium groove is designed to be in a semi-closed cylinder shape, and different calibration media can be replaced. And the connector adopts a C-shaped frame structure, so that the thermocouple is convenient to install and fix. The laser velocity measurement system obtains the immersion velocity of the thermocouple in real time based on a fixed-distance velocity measurement method. The temperature shielding structure effectively blocks high-temperature hot airflow, and errors caused by heating in the non-calibration stage of the sensor are avoided. The system sets the motion parameters of the push rod, controls the thermocouple to immerse into the medium, collects data in real time, and calculates the dynamic performance index.

Description

Technical Field

[0001] The utility model relates to the technical field of sensor calibration, in particular to an immersion system for dynamic calibration of thermocouples. Background Art

[0002] The purpose of dynamic calibration is to determine the dynamic response of a sensor and subsequently establish a sensor model. Immersion calibration involves rapidly inserting the thermocouple being calibrated into a calibration medium. This method, by momentarily changing the thermal equilibrium state of the sensor's sensitive element, studies the output signal patterns as the sensor reaches thermal equilibrium again, thereby determining the sensor's dynamic characteristic parameters. This method offers advantages such as a stable calibration source, controllable temperature, low experimental costs, and easy equipment operation, making it widely used in dynamic thermocouple calibration.

[0003] Currently, the commonly used immersion calibration system has the following problems:

[0004] 1) Due to different calibration media, the dynamic response time obtained by thermocouples varies significantly. To obtain dynamic performance indicators applicable to the test environment, a calibration medium similar to the temperature measurement environment should be used for dynamic performance calibration experiments. Currently, the immersion calibration method mainly uses high-temperature water as the calibration medium, and there is no effective solution to easily replace the calibration medium during the calibration experiment.

[0005] 2) The immersion speed is difficult to control. The dynamic response of a thermocouple in a fluid is closely related to its convective heat transfer coefficient, which in turn is affected by the immersion speed. Conventional free-fall calibration systems make it difficult to control the sensor's immersion speed, resulting in errors in the measured dynamic response of the sensor.

[0006] 3) The end velocity of immersion is unclear. Some free-fall calibration devices use theoretical formulas to calculate the end velocity, but due to the vibration caused by the damping of the support rod and the clearance fit during the sliding of the calibration platform, there is a large difference between the theoretical calculation value and the actual situation. Some electric calibration systems are limited by the stroke or drive source, and there will be a certain error between the end velocity and the actual set speed.

[0007] Patent CN115077744A discloses a thermocouple time constant measurement device and method based on the water bath method. This patent mainly addresses the problem that the hot air flow on the surface of the hot medium during the calibration process affects the sensor calibration results. Utility Model Content

[0008] To address the shortcomings of existing technologies, this utility model proposes an immersion system for dynamic thermocouple calibration, aiming to provide a highly accurate, efficient, and easy-to-operate and maintain thermocouple calibration solution. Through its innovative design, this device enables temperature calibration of thermocouples in a variety of environments, resolving the limitations of conventional calibration devices, which suffer from a single calibration environment and insufficient accuracy.

[0009] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0010] An immersion system for dynamic calibration of thermocouples, comprising a high-temperature oil tank, a dielectric tank, an electric push rod, a connector, a laser speed measurement system, a control system, a stand and a heat shielding structure. The high-temperature oil tank is arranged in the stand, and a calibration hole is provided on the surface of the high-temperature oil tank and cooperates with the dielectric tank. The electric push rod is mounted on the stand by means of threads and has a control system on one side. The control system is used to drive the motor of the electric push rod. The push rod movement direction of the electric push rod faces the calibration hole of the high-temperature oil tank. The top end of the push rod of the electric push rod is processed and installed with an external thread to cooperate with the connector. The connector fixes the thermocouple sensor. The laser speed measurement system comprises two displacement lasers, which are mounted on the stand between the connector and the high-temperature oil tank by means of threads; the heat shielding structure is installed between the high-temperature oil tank and the connector.

[0011] As a further improvement of the present invention, the heating medium in the high-temperature oil tank is dimethyl silicone oil, and the maximum heating temperature is 300°C.

[0012] As a further improvement of the present invention, the effective stroke range of the electric push rod is between 10 and 200 mm, and within the effective stroke range, the movement speed is between 0.1 and 1.2 m / s.

[0013] As a further improvement of the present invention, the medium tank is designed as a semi-closed cylinder with a flange, and the edge of the flange is clearance-matched with the concave platform of the calibration hole of the high-temperature oil tank.

[0014] As a further improvement of the present invention, the connector is designed as a C-shaped frame structure; a threaded hole is designed at the upper end to cooperate with the thread at the end of the electric push rod; a through hole is opened at the lower end for inserting the thermocouple sensor, and a locking screw is designed on the side wall of the through hole, and the thermocouple sensor is fixed by tightening the screw.

[0015] As a further improvement of the present invention, the heat shielding structure consists of a heat shielding plate, a support seat and a fixed head; the overall structure of the support seat is a column with a flange, and 4 fixing holes are opened at the flange end, which are connected to the high-temperature oil tank by screws, and an internal threaded hole is processed on the other side. The heat shielding plate is designed to be circular, and a through hole is opened near the edge, which is coaxial with the internal threaded hole of the support seat; the fixed head structure is a hexagonal screw type, and the lower end screw is tightened to match the internal threaded hole of the support seat. Beneficial effects

[0016] High-precision dynamic calibration: By integrating components such as a high-temperature oil tank, a dielectric tank, an electric actuator, and a laser speed measurement system, high-precision dynamic calibration of thermocouples in different calibration media is achieved. The high-temperature oil tank provides a stable heat source, and the dielectric tank allows for the exchange of different calibration media to study the dynamic response of the sensor in different environments.

[0017] Controllable immersion parameters: The electric push rod is combined with the control system to achieve precise control of immersion depth, speed, and posture. The wide effective travel range, fast movement speed, and small structure ensure the stability and accuracy of the calibration process.

[0018] Real-time speed measurement function: The laser speed measurement system is based on the fixed-distance speed measurement method and can obtain the immersion speed of the thermocouple in real time, providing the key speed parameter for calibration and helping to improve the accuracy of the calibration results.

[0019] Thermal shielding structure design: The thermal shielding structure effectively blocks the direct contact between the hot air flow generated during the heating process of the high-temperature oil tank and the thermocouple sensitive element, avoiding the sensor from being heated and generating thermoelectric potential during the non-calibration stage, thereby reducing calibration errors.

[0020] Modular design: The system adopts a modular design, including high-temperature oil tank, medium tank, electric push rod, connector, laser speed measurement system, control system and other modules, which is easy to assemble, disassemble and maintain, and improves the flexibility and scalability of the system.

[0021] Easy operation: The calibration process is clear and concise, including system connection, medium filling, sensor installation, temperature setting, motion parameter setting, calibration execution and data collection. The operation is simple and fast, reducing the difficulty and labor cost of calibration.

[0022] Wide application: The system can be widely used in the field of dynamic calibration of thermocouple sensors, and is particularly suitable for industrial scenarios that require high-precision and high-efficiency calibration, such as the power, petrochemical, metallurgy and other industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The overall structure diagram of the immersion system used for dynamic calibration of thermocouples;

[0024] Figure 2 This is the structural diagram of the dielectric tank;

[0025] Figure 3 This is the explosion structure diagram of the thermal shield.

[0026] Part Name:

[0027] 1. High-temperature oil tank; 2. Dielectric tank; 3. Electric push rod; 4. Connector; 5. Laser speed measurement system; 6. Control system; 7. Test stand; 8. Temperature shielding structure. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0029] The utility model discloses a structural diagram as shown in FIG. Figure 1 An immersion system for dynamic calibration of thermocouples is shown, which consists of a high-temperature oil tank 1, a medium tank 2, an electric push rod 3, a connector 4, a laser speed measurement system 5, a control system 6, a stand 7, and a temperature shielding structure 8.

[0030] The high-temperature oil tank 1 provides a stable heat source for calibration. The heating medium in the oil tank is dimethyl silicone oil, and the maximum heating temperature is 300°C. The surface of the oil tank is provided with a calibration hole, which, by cooperating with the medium tank 2, can realize dynamic calibration of thermocouples under different calibration media.

[0031] The electric push rod 3 is used to drive the calibrated thermocouple sensor to be immersed in the medium being measured; the electric push rod 3 is installed on the stand 7 through a thread, the push rod movement direction faces the oil tank calibration hole, and the top of the push rod is processed and installed with an external thread to cooperate with the connector 4; the control system 6 is used to drive the electric push rod motor and realize the control function of parameters such as movement direction, speed, and extension length;

[0032] Furthermore, the immersion system action mechanism formed by the combination of the electric push rod 3 and the control system 6 has the following advantages: 1) the immersion depth is controllable. Taking the electric push rod as an example, its effective stroke range is between 10 and 200 mm; 2) the immersion speed is controllable. Taking the electric push rod as an example, within the effective stroke range, the action speed is between 0.1 and 1.2 m / s; 3) the immersion posture is stable and the structural volume is small.

[0033] The medium tank 2 is as follows Figure 2 The design shown is a semi-enclosed cylinder with a flange. The flange edge has a clearance fit within the recessed portion of the oil tank calibration hole. During the experiment, the dynamic response of the sensor under different calibration media can be studied by changing the medium in the tank, such as water, oil, or paraffin.

[0034] The connector 4 is designed as a C-shaped frame structure; the upper end is designed with a threaded hole that matches the thread at the end of the electric push rod; the lower end is provided with a through hole for inserting the thermocouple sensor, and the side wall of the through hole is designed with a set screw, which is tightened to fix the sensor;

[0035] The laser speed measurement system 5 consists of two displacement lasers and a mounting bracket 7, which are screwed onto the bracket 7 between the connector and the high-temperature oil tank. The laser speed measurement system obtains the immersion speed based on the fixed-distance speed measurement method. When the electric push rod 3 drives the connector 4 and the calibrated thermocouple downward, the electric push rod 3 blocks the light path, causing the output value of the displacement laser to jump. The immersion speed can be calculated based on the time when the two displacement sensors successively output the jump signal and the known sensor installation distance.

[0036] The heat shielding structure 8 is as follows Figure 3 As shown, it is installed between the high-temperature oil tank 1 and the connector 4. This structure is used to prevent the hot air flow generated during the heating process of the high-temperature oil tank 1 from directly contacting the thermocouple sensitive element installed on the connector 4; it prevents the sensor from being heated during the non-calibration stage to generate thermoelectric potential, which may cause errors in the calibration results.

[0037] Furthermore, the heat shielding structure 8 is composed of a heat shielding plate, a support seat and a fixed head; the overall structure of the support seat is a column with a flange, and four fixing holes are opened at the flange end, which are connected to the high-temperature oil tank by screws, and an internal threaded hole is processed on the other side; the heat shielding plate is designed to be circular, and a through hole is opened near the edge, which is coaxial with the internal threaded hole of the support seat; the fixed head structure is a hexagonal screw type, and after the lower end screw is tightened in conjunction with the internal threaded hole of the support seat, the heat shielding plate can be effectively fixed.

[0038] Furthermore, the specific calibration process of the immersion system for dynamic calibration of thermocouples is introduced:

[0039] Connect the calibration system and perform power-on inspection and reset;

[0040] Fill the medium tank with calibration medium according to the calibration requirements;

[0041] Install the calibrated thermocouple on the connector and close the temperature shield;

[0042] Set the temperature of the high-temperature oil tank and heat the calibration medium in the oil tank and medium tank;

[0043] On the control system side, set the push rod movement speed and depth, and open the temperature shield after the calibration medium temperature stabilizes;

[0044] To calibrate the thermocouple, the control system commands the electric push rod to extend quickly, driving the connector and the calibrated thermocouple to be immersed in the medium, and at the same time obtain the accurate immersion speed parameters through the speed measuring laser;

[0045] The external data acquisition system acquires the thermocouple output signal in real time and calculates the dynamic performance indicators such as the time constant and response time (t50, t90, t99) of the calibrated thermocouple sensor based on the balance of the curve.

[0046] Through the control system, the electric push rod is retracted and the next round of calibration experiment is carried out according to the experimental results.

[0047] The above description is merely a preferred embodiment of the present invention and does not constitute any other limitation to the present invention. Any modification or equivalent variation based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. An immersion system for dynamic calibration of thermocouples, comprising a high-temperature oil tank (1), a medium tank (2), an electric push rod (3), a connector (4), a laser speed measurement system (5), a control system (6), a stand (7) and a temperature shielding structure (8), characterized in that: The high-temperature oil tank (1) is arranged in a bench (7). A calibration hole is provided on the surface of the high-temperature oil tank (1) and cooperates with the medium tank (2). The electric push rod (3) is installed on the bench (7) through a thread and has a control system (6) on one side. The control system (6) is used to drive the motor of the electric push rod (3). The push rod movement direction of the electric push rod (3) faces the calibration hole of the high-temperature oil tank (1). The top end of the push rod of the electric push rod (3) is processed and installed with an external thread to cooperate with the connector (4). The connector (4) fixes the thermocouple sensor. The laser speed measurement system (5) includes two displacement lasers. The displacement lasers are installed on the bench (7) between the connector (4) and the high-temperature oil tank (1) through a thread; the heat shielding structure (8) is installed between the high-temperature oil tank (1) and the connector (4).

2. The immersion system for dynamic calibration of thermocouples according to claim 1, characterized in that: The heating medium in the high-temperature oil tank (1) is dimethyl silicone oil, and the maximum heating temperature is 300°C.

3. The immersion system for dynamic calibration of thermocouples according to claim 1, characterized in that: The effective stroke range of the electric push rod (3) is between 10 and 200 mm, and within the effective stroke range, the movement speed is between 0.1 and 1.2 m / s.

4. The immersion system for dynamic calibration of thermocouples according to claim 1, characterized in that: The medium tank (2) is designed as a semi-closed cylinder with a flange, and the edge of the flange is clearance-matched with the concave platform of the calibration hole of the high-temperature oil tank (1).

5. The immersion system for dynamic calibration of thermocouples according to claim 1, characterized in that: The connector (4) is designed as a C-shaped frame structure; a threaded hole is designed at the upper end to match the thread of the end of the electric push rod (3); a through hole is provided at the lower end for inserting a thermocouple sensor, and a set screw is designed on the side wall of the through hole, and the thermocouple sensor is fixed by tightening the screw.

6. The immersion system for dynamic calibration of thermocouples according to claim 1, characterized in that: The heat shielding structure (8) is composed of a heat shielding plate, a support seat and a fixed head; the overall structure of the support seat is a column with a flange, and four fixing holes are opened at the flange end and connected to the high-temperature oil tank (1) through screws, and an internal threaded hole is processed on the other side. The heat shielding plate is designed to be circular, and a through hole is opened near the edge, which is coaxial with the internal threaded hole of the support seat; the fixed head structure is a hexagonal screw type, and the lower end screw is tightened to fit the internal threaded hole of the support seat.

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