Electronic balance and method for improving uncertainty of electronic balance

Abstract

The invention relates to an electronic balance and a method for improving uncertainty of the electronic balance, the electronic balance comprises a permanent magnet, the permanent magnet is fixedly connected with a base of the electronic balance, the permanent magnet is provided with a center hole, a stand column is arranged in the center hole, the upper end of the stand column is provided with a tray, and the lower part of the stand column is provided with a moving coil; the stand column is elastically connected with a base of the electronic balance through a tension spring, the stand column is provided with a heat dissipation channel, the lower end of the heat dissipation channel is communicated to the moving coil, and the upper end of the heat dissipation channel is communicated to the upper portion of the center hole. The structure of the electronic balance is improved, and the influence of demagnetization of the permanent magnet on the uncertainty of the electronic balance can be reduced. In addition, in combination with the method provided by the invention, whether the measurement uncertainty of the electronic balance is increased due to the demagnetization of the permanent magnet can be judged in time.

Description

Technical Field

[0001] The invention relates to an electronic balance and a method for improving the uncertainty of the electronic balance, belonging to the technical field of electronic balances. Background Art

[0002] An electronic balance is a high-precision weighing instrument, and its background technology involves multiple disciplines, including machinery, materials, electronic circuits, information processing, and precision manufacturing. With the development of science and technology and the improvement of industrialization, the demand for electronic balances has increased significantly, especially in key areas such as value transfer, food safety, biomedicine, and chemical analysis. Especially in the pharmaceutical industry, there is a lot of weighing of raw materials involved in drug research and development, and the weighing accuracy has a great impact on the research and development results. Therefore, there are high requirements for the measurement certainty of electronic balances.

[0003] like Figure 1 As shown in the figure, the working principle of the electronic balance is mainly based on the principle of electromagnetic force compensation balance, and the balance of force or torque is achieved through electronic devices. Specifically, the electronic balance measures the weight of an object through the electromagnetic force or Ampere force generated by the energized wire in the magnetic field. When the object is placed on the scale pan, its gravity will cause the moving coil to be subjected to force and produce displacement. After the distance sensor detects this displacement, it will send a signal, and the current in the moving coil will be changed through the regulator and amplifier until the distance sensor returns to the center position. At this time, the current intensity is proportional to the mass of the object, thereby achieving weighing.

[0004] When an electronic balance is weighing, environmental factors such as airflow, temperature, humidity, and vibration will affect the measurement accuracy. In addition, after repeated use of the electronic balance, the permanent magnet will demagnetize, which will increase the uncertainty of the electronic balance measurement, causing the balance reading to become unstable, fluctuating or drifting. There are many reasons for the demagnetization of the permanent magnet, such as multiple collisions and frictions between the column and the permanent magnet, or frequent heating of the permanent magnet, which will cause the permanent magnet to demagnetize. Summary of the invention

[0005] Aiming at the problem of inaccurate measurement caused by demagnetization of permanent magnets of electronic balance, the present invention first provides an electronic balance, and the specific scheme is as follows: An electronic balance comprises a permanent magnet, which is fixedly connected to a base of the electronic balance. The permanent magnet is provided with a central hole, a column is provided in the central hole, a tray is provided at the upper end of the column, a moving coil is provided at the lower part of the column, the column and the base of the electronic balance are elastically connected via a tension spring, a heat dissipation channel is provided at the column, the lower end of the heat dissipation channel is connected to the moving coil position, and the upper end of the heat dissipation channel is connected to the top of the central hole.

[0006] Furthermore, a rubber ring is provided on the upper part of the column, and the rubber ring is provided below the tray.

[0007] Furthermore, the heat dissipation channel includes a vertical hole and a side hole that are connected to each other. The vertical hole is arranged inside the column and along the height direction of the column, and the side hole is arranged on the side wall of the column.

[0008] Furthermore, the heat dissipation channel includes a vertical groove arranged on the side wall of the column.

[0009] The above improvements can reduce the degree of demagnetization of the permanent magnet of the electronic balance and improve the accuracy of the electronic balance. The present invention also takes into account the problem of determining the demagnetization of the permanent magnet of the electronic balance and proposes the following improvements, which can be used to timely determine whether the uncertainty of the electronic balance is increased due to the demagnetization of the permanent magnet.

[0010] Furthermore, a secondary coil is provided in the vertical slot, and the secondary coil is slidably arranged in the vertical slot along the height direction, and the secondary coil is connected to the constant current circuit; a distance sensor fixedly connected to the base is provided above the center hole, and the distance sensor is used to detect the position of the secondary coil.

[0011] Furthermore, a cover plate is provided above the central hole, the cover plate is provided with a convex plate corresponding to the vertical groove, and the distance sensor is fixed on the convex plate.

[0012] Furthermore, an upper support rod and a lower support rod are provided in the vertical slot, a vertical slide 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 arranged on the slide rod, and a spring is provided under the coil seat.

[0013] According to the electronic balance of 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 not loaded, the constant current circuit is powered on, the current of the secondary coil is constant, the distance sensor detects the position of the secondary coil, and the demagnetization degree of the permanent magnet of the electronic balance is determined according to the position signal of the secondary coil.

[0014] The present invention improves the structure of the electronic balance and can reduce the influence of permanent magnet demagnetization on the uncertainty of the electronic balance. In addition, in combination with the method of the present invention, it can also be timely determined whether the permanent magnet demagnetization causes the increase of the measurement uncertainty of the electronic balance. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the principle of an electronic balance.

[0016] Figure 2 Schematic diagram of the position of the rubber ring in the embodiment.

[0017] Figure 3 This is a schematic diagram of the column structure in Example 1.

[0018] Figure 4 This is a schematic diagram of the column structure in Example 2.

[0019] Figure 5Schematic diagram of the secondary coil in Example 3. DETAILED DESCRIPTION

[0020] The scheme of the present invention is described in detail below with reference to specific examples.

[0021] like Figure 1 The invention relates to an existing electronic balance structure, comprising a permanent magnet, which is fixedly connected to the base of the electronic balance, a central hole is provided in the permanent magnet, a column is provided in the central hole, a tray is provided at the upper end of the column, a moving coil is provided at the lower part of the column, and the column and the base of the electronic balance are elastically connected through a tension spring.

[0022] In order to solve the problem of permanent magnet demagnetization of electronic balance, the following improvements are made to the original structure of electronic balance, such as Figure 2 First, a rubber ring 2 is arranged on the column 1, and the rubber ring 2 is arranged under the tray 3 to reduce the demagnetization caused by the mechanical impact between the column and the permanent magnet 4. Second, a heat dissipation channel is arranged on the column 1. The electronic components inside the electronic balance generate heat when powered on, and demagnetization is prone to occur when the temperature of the permanent magnet rises. By setting a heat dissipation channel, internal heat dissipation is facilitated, solving the demagnetization problem caused by the increase in the temperature of the permanent magnet.

[0023] In the internal structure of the electronic balance, the moving coil 5 is the main heating element, so when setting the heat dissipation channel, the heat dissipation of the moving coil is mainly considered. Therefore, the heat dissipation channel needs to connect the heat source position of the moving coil with the outside of the electronic balance.

[0024] Example 1 like Figure 3 In this embodiment, the heat dissipation channel is designed to be a hollow structure of the column, that is, a vertical hole 6 is provided at the axis of the column 1, and a side hole 7 connected to the vertical hole is provided on the side wall of the column. The side hole at the bottom of the column is connected to the position of the moving coil, and the side hole at the top of the column is connected to the outside. As shown in the figure, there are a plurality of side holes, which are evenly distributed along the outer wall of the column.

[0025] Example 2 like Figure 4 In this embodiment, the structure of the heat dissipation channel is to open a vertical groove 8 on the outer wall of the column 1, and the vertical groove runs through the upper and lower parts of the column. There are multiple vertical grooves, which are arranged at equal intervals around the outer circumference of the column. The figure shows that 4 vertical grooves are set.

[0026] The uncertainty verification of the improved electronic balance and the original electronic balance was compared according to JJG1036-2008. The results are as follows:

[0027] From the above comparison, it can be seen that the improved electronic balance reduces the possibility of demagnetization of the permanent magnet, thereby reducing the uncertainty of the electronic balance measurement process and ensuring the accuracy and reliability of the measurement results.

[0028] Example 3 In order to solve the problem of permanent magnet demagnetization in electronic balance, based on Example 2, this embodiment sets a secondary coil in the vertical slot. Under the condition of constant current, the degree of demagnetization of the permanent magnet can be determined according to the position signal of the secondary coil. Specifically, Figure 5 , an upper support rod and a lower support rod are arranged in one of the vertical slots 8 of the column 1, a vertical slide rod 9 is connected between the upper support rod and the lower support rod, a secondary coil 10 is fixed on the coil seat, the coil seat is slidably arranged on the slide rod, and a spring 11 is arranged under the coil seat. A cover plate 12 is arranged above the center hole, the cover plate is provided with a convex plate corresponding to the vertical slot, the convex plate extends into the vertical slot where the secondary coil is arranged, and a distance sensor 13 is arranged on the convex plate, and the distance sensor adopts a laser distance sensor.

[0029] After the electronic balance is powered on and preheated, the constant current circuit is powered on without any load on the tray, and the distance sensor detects the position of the secondary coil. The degree of demagnetization of the permanent magnet of the electronic balance is determined based on the position signal of the secondary coil. The principle is that the energized coil is subjected to force in the magnetic field of the permanent magnet, and the magnitude of the force is related to the magnitude of the current and the strength of the magnetic field. Under the condition of constant current, the magnitude of the force on the secondary coil is only related to the magnetic field strength of the permanent magnet, and the height position of the secondary coil along the slide bar 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, which is fixedly connected to a base of the electronic balance, the permanent magnet is provided with a center hole, a column is provided in the center hole, a tray is provided at the upper end of the column, a moving coil is provided at the lower part of the column, and the column and the base of the electronic balance are elastically connected by a tension spring, characterized in that: The column is provided with a heat dissipation channel, the lower end of the heat dissipation channel is connected to the dynamic coil position, and the upper end of the heat dissipation channel is connected to the upper part of the center hole.

2. The electronic balance according to claim 1, characterized in that: A rubber ring is arranged on the upper part of the column, and the rubber ring is arranged under the tray.

3. The electronic balance according to claim 1, characterized in that: The heat dissipation channel comprises a vertical hole and a side hole which are connected to each other. The vertical hole is arranged inside the column and along the height direction of the column, and the side hole is arranged on the side wall of the column.

4. The electronic balance according to claim 1, characterized in that: The heat dissipation channel includes a vertical groove arranged on the side wall of the column.

5. The electronic balance according to claim 4, characterized in that: A secondary coil is arranged in the vertical slot and is slidably arranged in the vertical slot along the height direction; a distance sensor fixedly connected to the base is arranged above the central hole and is used to detect the position of the secondary coil.

6. The electronic balance according to claim 5, characterized in that: A cover plate is arranged above the central hole, the cover plate is provided with a convex plate corresponding to the vertical groove, and the distance sensor is fixed on the convex plate.

7. The electronic balance according to claim 5, characterized in that: An upper support rod and a lower support rod are arranged in the vertical slot, 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 arranged on the sliding rod, and a spring is arranged under the coil seat.

8. A method for improving the uncertainty of an electronic balance, characterized in that: The invention uses an electronic balance as described in any one of claims 5 to 7. After the electronic balance is powered on and preheated, the secondary coil is powered on and the current is kept constant under the condition that there is no load on the tray. The distance sensor detects the position of the secondary coil, and the accuracy of the electronic balance is determined according to the position signal of the secondary coil.

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