A calibration device for a magnetic stirrer

Abstract

This invention relates to a calibration device for a magnetic stirrer, comprising a support frame, a crossbeam, and a rotating shaft rotatably mounted on the crossbeam. A follower blade is fixed on the rotating shaft, with one end of the follower blade extending into the liquid being stirred and rotating with it. The support frame also includes a height adjustment mechanism for adjusting the height of the rotating shaft, and a speed sensor for detecting the rotational speed of the rotating shaft is mounted on the crossbeam. The magnetic stirrer rotates the liquid in the mixing cup via a magnetic stir bar, forming a conical vortex at the center of the liquid, wider at the top and narrower at the bottom. The end of the follower blade, away from the rotating shaft, penetrates the inner wall of the conical vortex and extends into the liquid. The liquid carries the follower blade along with it, thus the rotational speed of the follower blade directly represents the rotational speed of the liquid being stirred. The output speed of the magnetic stirrer is calibrated by detecting the rotational speed of the rotating shaft using the speed sensor.

Description

Technical Field

[0001] This invention relates to the field of verification and calibration, and more particularly to a calibration device for a magnetic stirrer. Background Technology

[0002] Magnetic stirrers are a common stirring device in laboratories, used to mix liquid materials in a container evenly.

[0003] Magnetic stirrers in the prior art, such as Figure 1 As shown: It includes a main unit 5 and a material cup 1. The main unit 5 is equipped with a magnetic rotor driven by a motor, and also includes a magnetic stirrer 2 placed in the material cup during use. The main unit is equipped with a switch 8, a speed adjustment knob 6 and a temperature adjustment knob 7.

[0004] In use, place the mixing cup 1 on the main unit 5, place the magnetic stir bar 2 inside the mixing cup, add the liquid to be stirred 4 to the mixing cup, turn on the main unit, and when the magnetic rotor rotates, the non-contact magnetic field causes the magnetic stir bar to rotate around its vertical axis. The magnetic stir bar carries the liquid to be stirred in the mixing cup, thus making the liquid evenly mixed. As the liquid is rotated by the magnetic stir bar, a cone-shaped vortex, wider at the top and narrower at the bottom, will form at the center of the liquid. The temperature adjustment knob can be used to heat the liquid and adjust its temperature. The speed adjustment knob is used to control the speed of the magnetic stir bar.

[0005] According to the relevant calibration specifications, the output speed and output temperature of the magnetic stirrer need to be calibrated. Strictly speaking, the output speed of the magnetic stirrer refers to the speed of the magnetic stir bar, which corresponds to the rotational speed of the liquid being stirred. However, the existing calibration method directly calibrates the speed of the magnetic rotor of the main unit. The magnetic stir bar and the magnetic rotor transmit force through a non-contact magnetic field. The speed of the magnetic stir bar is lagging and inconsistent with the speed of the magnetic rotor. Directly measuring the speed of the magnetic rotor cannot truly reflect the speed of the magnetic stir bar and the liquid being stirred. Therefore, the output speed of the magnetic stirrer cannot be accurately calibrated. In addition, when calibrating the output temperature of the magnetic stirrer, a thermocouple is directly inserted into the liquid to measure the liquid temperature. The thermocouple is stationary, while the liquid is rotating at high speed. There will be a temperature gradient field between the two relatively moving parts. Therefore, in the existing technology, the thermocouple cannot accurately measure the liquid temperature, and the output temperature of the magnetic stirrer cannot be accurately calibrated. Summary of the Invention

[0006] The purpose of this invention is to provide a calibration device for a magnetic stirrer that can calibrate the output speed of the magnetic stirrer.

[0007] To solve the above-mentioned technical problems, the technical solution of the calibration device for a magnetic stirrer in this invention is as follows: A calibration device for a magnetic stirrer includes a device support, which includes a device beam. A rotating shaft with its lower end inserted into a conical vortex formed by the liquid being stirred is rotatably mounted on the device beam. A follower blade is fixed on the rotating shaft, with one end of the follower blade away from the rotating shaft inserted into the liquid being stirred and rotating with the liquid. The device support is also provided with a height adjustment mechanism for adjusting the height of the rotating shaft, and a speed sensor for detecting the rotational speed of the rotating shaft is provided on the device beam.

[0008] Furthermore, the device support includes a device column, and the height adjustment mechanism includes a guide sleeve fixed to one end of the device beam. The guide sleeve is guided onto the device column in the vertical direction, and a tightening screw is threaded onto the guide sleeve to tighten the device column and fix the height of the guide sleeve.

[0009] Furthermore, the speed sensor is a speed encoder mounted on the crossbeam of the device.

[0010] Furthermore, the follower blade includes a blade sleeve fixedly connected to the rotating shaft. The follower blade also includes at least two blade units arranged circumferentially along the blade sleeve. Each blade unit includes a body section connected to the blade sleeve and a telescopic section that telescopically engages with the body section along the radial direction of the blade sleeve. A blade reset tension spring is provided between the body section and the telescopic section. The telescopic section is used to extend into the liquid being stirred.

[0011] Furthermore, temperature sensors are installed on the extension sections of each individual blade.

[0012] Furthermore, there are two individual blades, which are evenly spaced along the circumference of the blade sleeve.

[0013] Furthermore, the main body section is a circular rod structure, and the telescopic section is a vertical plate structure.

[0014] The beneficial effects of this invention are as follows: In use, the magnetic stirrer rotates the liquid being stirred in the cup through the magnetic stir bar. A conical vortex with a larger top and a smaller bottom is formed in the center of the liquid being stirred. The end of the follower blade away from the rotating shaft passes through the inner wall of the conical vortex and extends into the liquid being stirred. The liquid being stirred rotates along with the follower blade. Therefore, the rotation speed of the follower blade is the rotation speed of the liquid being stirred, which in turn represents the rotation speed of the magnetic stir bar. The output speed of the magnetic stirrer is calibrated by detecting the rotation speed of the rotating shaft through a speed sensor. Attached Figure Description

[0015] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings. In the drawings, several embodiments of this disclosure are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding portions, wherein: Figure 1 This is a schematic diagram of the structure of the magnetic stirrer in the background art of this invention; Figure 2 This is a usage diagram of an embodiment of the calibration device for the magnetic stirrer in this invention; Figure 3 yes Figure 2 Schematic diagram of the structure of the follower blade; Figure 4 yes Figure 3 Top view; Figure 5 This is a schematic diagram of the interaction between the follower blades and the liquid being stirred; Explanation of reference numerals in the attached diagram: 1. Feed cup; 2. Magnetic stirrer; 3. Conical vortex; 4. Liquid being stirred; 5. Main unit; 6. Speed ​​adjustment knob; 7. Temperature adjustment knob; 8. Switch button; 9. Device support; 10. Device column; 11. Guide sleeve; 12. Tightening screw; 13. Device crossbeam; 14. Speed ​​encoder; 15. Rotating shaft; 16. Follower blade; 17. Blade sleeve; 18. Individual blade; 19. Return spring; 20. Telescopic section; 21. Temperature sensor; 22. Main body section; 23. Lateral adjustment block. Detailed Implementation

[0016] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0017] It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0018] An embodiment of a calibration device for a magnetic stirrer in this invention includes a device support 9, which includes a device crossbeam 13 and a device column 10. The device crossbeam 13 includes a crossbeam body, and a transverse adjustment block 23 is mounted on the crossbeam body along its length direction. The crossbeam body has a square cross-section. The transverse adjustment block has a square guide hole adapted to the square structure. A rotating shaft 15 with a rotation axis extending in the vertical direction is rotatably mounted on the transverse adjustment block. The lower end of the rotating shaft is used to extend into the conical vortex 3 formed by the stirred liquid.

[0019] A follower blade 16 is fixed on the rotating shaft. The end of the follower blade 16 away from the rotating shaft is used to extend into the liquid being stirred and rotate together with the liquid being stirred. The device support is also provided with a height adjustment mechanism for adjusting the height of the rotating shaft. A speed sensor for detecting the rotation speed of the rotating shaft is provided on the transverse adjustment block. In this embodiment, the speed sensor is a speed encoder 14 provided on the transverse adjustment block, and the rotating shaft passes through the inner hole of the speed encoder.

[0020] The height adjustment mechanism includes a guide sleeve 11 fixed to one end of the device crossbeam. The guide sleeve 11 is guided onto the device column in a vertical direction. A tightening screw 12 is radially threaded onto the guide sleeve to tighten the device column and fix the height of the guide sleeve. In this embodiment, the device column is a circular column, and the inner hole of the guide sleeve is a matching circular hole. That is, after loosening the tightening screw, the device crossbeam can not only move up and down relative to the device column, but also rotate relative to the device column. After the height and angle of the device crossbeam are adjusted to the correct positions, tightening the tightening screw will fix the position of the device crossbeam.

[0021] The follower blade 16 includes a blade sleeve 17 fixedly connected to the rotating shaft. The follower blade also includes two blade units 18 evenly spaced along the circumference of the blade sleeve. Each blade unit 18 includes a body section 22 connected to the blade segment and a telescopic section 20 that extends and retracts with the body section along the radial direction of the blade sleeve. One end of the body section 22 is fixed to the blade sleeve 17. A blade return spring 19 is provided between the body section 22 and the telescopic section 20. One end of the blade return spring 19 is fixed to the body section, and the other end is fixed to the telescopic section 20. The telescopic section is used to extend into the liquid being stirred.

[0022] In this embodiment, the main body section is a circular rod structure, and the telescopic section 20 is a vertical plate structure. In this way, when the stirred liquid rotates, the force on the circular rod is smaller, while the force on the vertical plate is larger.

[0023] The telescopic section 20 is anti-rotationally engaged with the main body section. Specifically, the anti-rotation means is that the main body section is provided with an anti-rotation square hole extending radially along the blade sleeve, and the telescopic section has an anti-rotation square shaft adapted to the anti-rotation square hole. The anti-rotation square shaft and the anti-rotation square hole are guided and moved radially along the blade sleeve.

[0024] When in use, adjust the angle and height of the device's crossbeam, and place the follower blade into the liquid to be stirred in the cup from top to bottom. Adjust the lateral position of the horizontal adjustment block so that the rotating shaft is in the center of the cup. Then turn on the magnetic stirrer. The magnetic stirrer drives the liquid to be stirred in the cup to rotate through the magnetic stir bar. The liquid to be stirred generates a conical vortex with the center line of the cup as the center, which is larger at the top and smaller at the bottom. The main body section runs radially across the inner wall of the conical vortex, while the telescopic section extends into the interior of the liquid to be stirred. Specifically, at the corresponding height position, the telescopic section is located at the center position between the inner wall of the conical vortex and the inner wall of the cup. This is because the flow velocity on the inner wall of the conical vortex is different from the flow velocity at the inner wall of the cup for the liquid to be stirred. Only the fluid velocity at the middle position can truly reflect the average rotational speed of the liquid to be stirred. In this embodiment, the main body section is a cylindrical structure, so the main body section that spans the inner wall of the conical vortex will not be subjected to too much force from the stirred liquid. The telescopic section of the vertical plate structure is subjected to the force from the stirred liquid at the corresponding position. The force on the telescopic section determines the rotation speed of the follower blade, so that the follower blade can be the same as the rotation speed of the stirred liquid at the corresponding position, thereby accurately representing the rotation speed of the stirred liquid. The rotation speed of the stirred liquid is the corresponding rotation speed of the magnetic stir bar. The reason for using a telescopic structure is that when the rotational speed of the magnetic stirrer increases, the rotational speed of the liquid being stirred also increases, and the inner diameter of the conical vortex increases. The position that reflects the average rotational speed of the liquid being stirred will move towards the inner wall of the cup. Since the follower blades use a telescopic structure, when the rotational speed of the magnetic stirrer increases, the rotational speed of the follower blades will also increase. The telescopic section will extend to a position further away from the rotation axis due to the increase in centrifugal force, thus adapting to the increase in the inner diameter of the conical vortex. The telescopic section still moves to the center position between the inner wall of the conical vortex and the inner wall of the cup, accurately representing the rotational speed of the liquid being stirred, and thus accurately representing the rotational speed of the magnetic stirrer.

[0025] The temperature sensor installed on the telescopic section rotates synchronously with the liquid being stirred. There is no relative velocity between the temperature sensor and the liquid, thus allowing for accurate measurement of the temperature at the corresponding location. However, there is a discrepancy between the temperature on the inner wall of the conical vortex and the internal temperature of the liquid. In this invention, the temperature sensor extends with the telescopic section to the center position between the inner wall of the conical vortex and the inner wall of the container. Therefore, it can accurately measure the internal temperature of the liquid being stirred. When the rotational speed of the magnetic stir bar changes, the inner diameter of the conical vortex changes. However, regardless of the change in the inner diameter of the conical vortex, the temperature sensor moves with the telescopic section to the center position between the inner wall of the conical vortex and the inner wall of the container, ensuring accurate temperature measurement. Temperature sensors are installed on each telescopic section to ensure uniform force on each individual blade during rotation. Simultaneously, the temperature of the liquid being stirred at multiple locations in the container can be measured, and the output temperature of the magnetic stirrer is calibrated using the average value of the temperature sensors.

[0026] In the foregoing description of this specification, unless otherwise expressly specified and limited, the terms "fixed," "installed," "connected," or "linked" should be interpreted broadly. For example, the term "linked" can refer to a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; or it can refer to the internal communication of two components or the interaction between two components. Therefore, unless otherwise expressly limited in this specification, those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] Based on the above description in this specification, those skilled in the art will also understand that terms used, such as "upper," "lower," "front," "rear," "left," "right," "length," "width," "thickness," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," "center," "longitudinal," "transverse," "clockwise," or "counterclockwise," are terms indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings of this specification. They are only for the purpose of facilitating the explanation of the present invention and simplifying the description, and do not imply that the devices or elements involved must have the specific orientation, or be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms should not be understood or interpreted as limitations on the present invention.

[0028] Furthermore, the terms "first" or "second," etc., used in this specification to refer to numbers or ordinal numbers are for descriptive purposes only and should not be construed as indicating, explicitly or implicitly, relative importance or specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this specification, "a plurality of" means at least two, such as two, three, or more, unless otherwise explicitly specified.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A calibration device for a magnetic stirrer, characterized in that: The device includes a support frame, which includes a crossbeam. A rotating shaft, with its lower end extending into a conical vortex formed by the liquid being stirred, is rotatably mounted on the crossbeam. Follower blades are fixed to the rotating shaft, with one end of the follower blade extending into the liquid being stirred and rotating with it. The support frame also includes a height adjustment mechanism for adjusting the height of the rotating shaft. A speed sensor for detecting the rotational speed of the rotating shaft is mounted on the crossbeam. The follower blades include a blade sleeve fixedly connected to the rotating shaft and at least two blade units spaced circumferentially along the blade sleeve. Each blade unit includes a body section connected to the blade sleeve and a telescopic joint that extends and retracts with the body section radially along the blade sleeve. The main body section and the telescopic section are equipped with a blade return spring. The telescopic section is used to extend into the liquid being stirred. When the rotation speed of the magnetic stir bar increases, the rotation speed of the liquid being stirred also increases, and the inner diameter of the conical vortex increases. The position that reflects the average rotation speed of the liquid being stirred will move towards the inner wall of the cup. Since the follower blade adopts a telescopic structure, when the rotation speed of the magnetic stir bar increases, the rotation speed of the follower blade also increases. The telescopic section will extend to a position further away from the rotation axis due to the increase in centrifugal force, thus adapting to the increase in the inner diameter of the conical vortex. The telescopic section moves to the center position between the inner wall of the conical vortex and the inner wall of the cup. A temperature sensor is installed on the telescopic section of each blade unit.

2. The calibration device for a magnetic stirrer according to claim 1, characterized in that: The device support includes a device column, and the height adjustment mechanism includes a guide sleeve fixed to one end of the device beam. The guide sleeve is guided onto the device column in the vertical direction, and a tightening screw is threaded onto the guide sleeve to tighten the device column and fix the height of the guide sleeve.

3. The calibration device for a magnetic stirrer according to claim 1, characterized in that: The speed sensor is a speed encoder mounted on the crossbeam of the device.

4. The calibration device for a magnetic stirrer according to claim 1, characterized in that: There are two individual blades, which are evenly spaced along the circumference of the blade sleeve.

5. The calibration device for a magnetic stirrer according to claim 1, characterized in that: The main body section is a circular rod structure, and the telescopic section is a vertical plate structure.

Images