An electronic balance and a method for improving the uncertainty of an electronic balance

Abstract

The application relates to an electronic balance and a method for improving the uncertainty of the electronic balance, the electronic balance comprising a permanent magnet, the permanent magnet being fixedly connected with a base of the electronic balance, the permanent magnet being provided with a center hole, a stand being arranged in the center hole, an upper end of the stand being provided with a tray, a lower part of the stand being provided with a moving coil, the stand being elastically connected with the base of the electronic balance through a tension spring, the stand being provided with a heat dissipation channel, a lower end of the heat dissipation channel being communicated to the position of the moving coil, and an upper end of the heat dissipation channel being communicated to the upper part of the center hole. The structure of the electronic balance is improved, and the influence of the demagnetization of the permanent magnet on the uncertainty of the electronic balance can be reduced. In addition, the method of the application can also be used to timely judge whether the demagnetization of the permanent magnet causes the increase of the measurement uncertainty of the electronic balance.

Description

Technical Field

[0001] This invention relates to an electronic balance and a method for improving the uncertainty of an electronic balance, belonging to the field of electronic balance technology. Background Technology

[0002] Electronic balances are high-precision weighing instruments whose underlying technologies involve multiple disciplines, including mechanics, materials science, electronic circuits, information processing, and precision manufacturing. With technological advancements and increased industrialization, the demand for electronic balances has increased significantly, particularly in key areas such as metrological transfer, food safety, biomedicine, and chemical analysis. Especially in the pharmaceutical industry, drug development involves extensive weighing of raw materials, and the accuracy of these weighings greatly impacts the research results; therefore, high metrological certainty is required for electronic balances.

[0003] like Figure 1 As shown, the working principle of an electronic balance is mainly based on the principle of electromagnetic force compensation balance, achieving force or torque balance through electronic devices. Specifically, an electronic balance measures the weight of an object by using the electromagnetic force, or Ampere force, generated in a magnetic field by a current-carrying conductor. When an object is placed on the weighing pan, its gravity causes a force to be applied to the moving coil, resulting in displacement. After the distance sensor detects this displacement, it sends a signal, which changes the current in the moving coil through a regulator and amplifier until the distance sensor returns to the center position. At this point, the current intensity is proportional to the mass of the object, thus achieving weighing.

[0004] When using an electronic balance, environmental factors such as airflow, temperature, humidity, and vibration can affect the accuracy of the measurement. Furthermore, after repeated use, the permanent magnets may demagnetize, increasing the uncertainty of the measurement and causing the balance readings to become unstable, fluctuating, or drifting. There are many reasons for permanent magnet demagnetization, such as repeated collisions and friction between the column and the permanent magnet, or frequent heating of the permanent magnet, all of which can lead to demagnetization. Summary of the Invention

[0005] To address the problem of inaccurate measurement caused by demagnetization of the permanent magnet in electronic balances, this invention first provides an electronic balance, the specific solution of which is as follows:

[0006] An electronic balance includes a permanent magnet fixedly connected to the base of the electronic balance. The permanent magnet has a central hole, and a column is provided inside the central hole. A tray is provided at the upper end of the column, and a moving coil is provided at the lower part of the column. The column and the base of the electronic balance are elastically connected by a tension spring. The column has a heat dissipation channel, the lower end of which is connected to the moving coil, and the upper end of which is connected to the top of the central hole.

[0007] Furthermore, a rubber ring is provided on the upper part of the column, and the rubber ring is located below the tray.

[0008] Furthermore, the heat dissipation channel includes interconnected vertical holes and side holes. The vertical holes are located inside the column and are set along the height direction of the column, while the side holes are located on the side wall of the column.

[0009] Furthermore, the heat dissipation channel includes vertical grooves located on the side wall of the column.

[0010] The above improvements can reduce the degree of demagnetization of the permanent magnet in the electronic balance and improve the accuracy of the electronic balance. This invention also considers the problem of determining whether the permanent magnet in the electronic balance is demagnetized, and proposes the following improvements, which can be used to promptly determine whether the uncertainty of the electronic balance has increased due to the demagnetization of the permanent magnet.

[0011] Furthermore, a secondary coil is provided in the vertical groove, which is slidably disposed in the vertical groove along the height direction and is connected to a constant current circuit; a distance sensor is provided above the central hole and is fixedly connected to the base, and the distance sensor is used to detect the position of the secondary coil.

[0012] Furthermore, a cover plate is provided above the central hole, and the cover plate has a protrusion plate corresponding to the vertical groove, on which the distance sensor is fixed.

[0013] Furthermore, the vertical groove is provided with an upper support rod and a lower support rod, and a vertical sliding rod is connected between the upper support rod and the lower support rod. The secondary coil is fixed on the coil seat, the coil seat is slidably mounted on the sliding rod, and a spring is provided below the coil seat.

[0014] According to the present invention, a method for improving the uncertainty of the electronic balance is further disclosed. After the electronic balance is powered on and preheated, under the condition that the tray is unloaded, the constant current circuit is powered on, the magnitude of the secondary coil current is constant, the distance sensor detects the position of the secondary coil, and the degree of demagnetization of the permanent magnet of the electronic balance is determined according to the position signal of the secondary coil.

[0015] This invention improves the structure of the electronic balance, reducing the impact of permanent magnet demagnetization on the uncertainty of the electronic balance. Furthermore, combined with the method of this invention, it can also promptly determine whether permanent magnet demagnetization is causing an increase in the measurement uncertainty of the electronic balance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram illustrating the principle of an electronic balance.

[0017] Figure 2 This is a schematic diagram showing the position of the rubber ring in the embodiment.

[0018] Figure 3 This is a schematic diagram of the column structure in Example 1.

[0019] Figure 4 This is a schematic diagram of the column structure in Example 2.

[0020] Figure 5 This is a schematic diagram of the secondary coil in Example 3. Detailed Implementation

[0021] The following detailed explanation of the invention patent solution, using specific examples, illustrates the invention patent in detail.

[0022] like Figure 1 It is an existing electronic balance structure, including a permanent magnet, which is fixedly connected to the base of the electronic balance. The permanent magnet has a central hole, and a column is installed inside the central hole. A tray is installed at the upper end of the column, and a moving coil is installed at the lower part of the column. The column and the base of the electronic balance are elastically connected by a tension spring.

[0023] To address the demagnetization problem of permanent magnets in electronic balances, the following improvements were made to the original electronic balance structure, such as... Figure 2 First, a rubber ring 2 is installed on the column 1, positioned below the tray 3, to reduce demagnetization caused by mechanical impact between the column and the permanent magnet 4. Second, a heat dissipation channel is installed on the column 1. When the electronic components inside the balance are powered on, they generate heat, and the permanent magnet is prone to demagnetization when its temperature rises. The heat dissipation channel facilitates internal heat dissipation, solving the demagnetization problem caused by the increased temperature of the permanent magnet.

[0024] In the internal structure of the electronic balance, the moving coil 5 is the main heat-generating component. Therefore, when designing the heat dissipation channel, the heat dissipation of the moving coil is the primary consideration. Thus, the heat dissipation channel needs to connect the heat source of the moving coil to the outside of the electronic balance.

[0025] Example 1

[0026] like Figure 3 In this embodiment, the heat dissipation channel is designed with a hollow column structure. Specifically, a vertical hole 6 is provided at the axis of the column 1, and side holes 7 communicating with the vertical hole are provided on the side wall of the column. The side holes at the lower part of the column communicate with the moving coil, and the side holes at the upper part of the column communicate with the outside. The illustration shows several side holes evenly distributed along the outer wall of the column.

[0027] Example 2

[0028] like Figure 4 In this embodiment, the heat dissipation channel structure consists of vertical grooves 8 formed on the outer wall of the column 1, which extend through the upper and lower parts of the column. Multiple vertical grooves are provided, evenly spaced around the outer circumference of the column; the illustration shows four vertical grooves.

[0029] The improved electronic balance was compared with the original electronic balance in terms of uncertainty verification according to JJG1036-2008. The results are shown in the table below:

[0030]

[0031] The above comparison shows that the improved electronic balance reduces the possibility of permanent magnet demagnetization, thereby reducing the uncertainty of the electronic balance measurement process and ensuring the accuracy and reliability of the measurement results.

[0032] Example 3

[0033] To address the demagnetization problem of permanent magnets in electronic balances, this embodiment, based on Example 2, incorporates a secondary coil within the vertical slot. Under constant current conditions, the degree of demagnetization of the permanent magnet can be determined based on the position signal of the secondary coil. Specifically, as shown... Figure 5 An upper support rod and a lower support rod are installed in one of the vertical slots 8 of the column 1. A vertical slide rod 9 connects the upper and lower support rods. The secondary coil 10 is fixed on the coil seat, which is slidably mounted on the slide rod. A spring 11 is installed below the coil seat. A cover plate 12 is installed above the central hole. The cover plate has a protrusion plate corresponding to the vertical slot. The protrusion plate extends into the vertical slot where the secondary coil is located. A distance sensor 13 is installed on the protrusion plate. The distance sensor is a laser rangefinder.

[0034] After the electronic balance has been preheated by power, with no load on the tray, the constant current circuit is energized, and the distance sensor detects the position of the secondary coil. The degree of demagnetization of the permanent magnet in the electronic balance is determined based on the position signal of the secondary coil. The principle is that the energized coil experiences a force in the magnetic field of the permanent magnet. The magnitude of the force is related to the magnitude of the current and the strength of the magnetic field. Under constant current conditions, the magnitude of the force on the secondary coil is only related to the magnetic field strength of the permanent magnet. The height of the secondary coil along the slider is related to the magnitude of the force. Therefore, the magnetic field strength of the permanent magnet can be determined based on the position signal of the secondary coil detected by the distance sensor.

Claims

1. An electronic balance, comprising a permanent magnet fixedly connected to a base of the electronic balance, the permanent magnet having a central hole, a column disposed within the central hole, a tray disposed at the upper end of the column, a moving coil disposed at the lower part of the column, and the column and the base of the electronic balance being elastically connected by a tension spring, characterized in that: The column is equipped with heat dissipation channels, the lower end of which is connected to the moving coil position, and the upper end of which is connected to the top of the central hole. The heat dissipation channel includes a vertical groove on the side wall of the column; a secondary coil is provided in the vertical groove, and the secondary coil is slidably disposed in the vertical groove along the height direction; a distance sensor is provided above the central hole and is fixedly connected to the base, and the distance sensor is used to detect the position of the secondary coil.

2. The electronic balance according to claim 1, characterized in that: The upper part of the column is equipped with a rubber ring, which is located below the tray.

3. The electronic balance according to claim 1, characterized in that: The heat dissipation channel includes interconnected vertical holes and side holes. The vertical holes are located inside the column and are set along the height direction of the column, while the side holes are located on the side wall of the column.

4. The electronic balance according to claim 1, characterized in that: A cover plate is provided above the central hole, and the cover plate has a protrusion plate corresponding to the vertical groove. The distance sensor is fixed on the protrusion plate.

5. The electronic balance according to claim 4, characterized in that: The vertical groove is provided with an upper support rod and a lower support rod, and a vertical sliding rod connects the upper support rod and the lower support rod. The secondary coil is fixed on the coil seat, and the coil seat is slidably mounted on the sliding rod. A spring is provided below the coil seat.

6. A method for improving the uncertainty of an electronic balance, characterized in that, The electronic balance described in any one of claims 1-5 is used. After the electronic balance is powered on and preheated, the secondary coil is powered on under the condition that there is no load on the tray, and the current is kept constant. The distance sensor detects the position of the secondary coil, and the accuracy of the electronic balance is determined based on the position signal of the secondary coil.

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