JP4117455B2 - Electronic weighing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic weighing device capable of weighing a minute amount of gas adsorbed on a sample.
[0002]
[Prior art]
Conventionally, an electromagnet is hung on the underfloor hanging hook of an electronic balance, and a sealed container is placed directly under the electromagnet, and a permanent magnet, in which the sample is hung with a wire, is lifted by the electromagnet and held in the air to measure the weight increase / decrease of the sample. There is something to do.
[0003]
However, in the method in which the sample is suspended under the permanent magnet, heat is transferred upward by convection when the sample is heated, so that the permanent magnet is heated. There was a problem that it was likely to become unstable.
[0004]
In addition, since the electromagnet is suspended from the electronic balance and the problem of heat convection, it is necessary to increase the distance between the permanent magnet and the sample, resulting in an increase in the height of the apparatus.
[0005]
In addition, since the sample is located in the lower part of the sealed container, there is a problem that it is difficult to mount and remove the sample.
[0006]
[Problems to be solved by the invention]
The present invention has been proposed in view of the above-mentioned problems of the prior art, and can prevent performance deterioration of a permanent magnet due to thermal convection when measuring a weight while heating a sample, and more than conventional. An object of the present invention is to provide an electronic weighing device that can be miniaturized.
[0007]
[Means for Solving the Problems]
An electronic weighing device according to a first invention includes an electronic balance, a fixing member, a sealed container, a magnetic levitation body, a light emitting unit, a light receiving unit, and a current control device. The fixing member has an insertion hole, a cylindrical permanent magnet, and a floating position control electromagnet. The insertion hole extends along the vertical direction. The cylindrical permanent magnet is magnetized in the axial direction, and is disposed in the upper part of the insertion hole so that the axis is along the vertical direction. The flying position control electromagnet is disposed vertically below the cylindrical permanent magnet. And this fixing member is installed on an electronic balance. The sealed container has a first cylinder part , a second cylinder part, and an upper lid part. The first cylindrical portion is inserted into the insertion hole through the hole of the cylindrical permanent magnet so as not to contact the wall of the insertion hole, the cylindrical permanent magnet, and the flying position control electromagnet, and the lower end is closed. . The second tube portion is disposed above the first tube portion, and the lower end is connected to the upper end of the first tube portion. An upper cover part obstruct | occludes the upper end of a 2nd cylinder part. The magnetic levitation body has a rod-shaped member, a sample container, a light shielding portion, an upper permanent magnet, and a lower permanent magnet. The sample container is fixed to the rod-shaped member. The light shielding portion is fixed to the rod-shaped member. The upper permanent magnet is magnetized in a direction opposite to the magnetization direction of the cylindrical permanent magnet, and is fixed to a portion of the rod-like member below the fixing position of the sample container. The lower permanent magnet is fixed to a portion of the rod-like member below the fixing position of the upper permanent magnet. The lower permanent magnet attracts the flying position control electromagnet. The magnetic levitation body is housed in a sealed container so that the sample container and the light-shielding portion are housed in the second tube portion, and the upper permanent magnet and the lower permanent magnet are housed in the first tube portion. The light receiving part is arranged to face the light emitting part with the light shielding part interposed therebetween. The current control device controls the current that flows through the flying position control electromagnet based on the amount of light received by the light receiving unit.
[0008]
In this electronic weighing device, the magnetic levitation body is balanced by controlling the attractive force acting between the floating position control electromagnet and the lower permanent magnet with respect to the attractive force acting between the cylindrical permanent magnet and the upper permanent magnet. Can surface. For this reason, in this electronic weighing device, the weight of the fixing member and the magnetic levitation body can be collectively measured. In this electronic weighing device, the sample container is provided on the top of the magnetic levitation body. For this reason, in this electronic weighing device, the influence on the magnetic levitation performance due to convection during heating can be minimized. Moreover, in this electronic weighing apparatus, it is not necessary to use the wire for suspension. For this reason, in this electronic weighing apparatus, it can be set as a structure with low height. Therefore, this electronic weighing device can be made smaller than before. As a result, this electronic weighing device can be manufactured at low cost. Further, in this electronic weighing apparatus, if the cylindrical fixing member and the magnetic levitation body are lightened, the weight increase / decrease of the sample can be measured with very high accuracy.
[0009]
The electronic weighing device according to the second invention is the electronic weighing device according to the first invention, further comprising a heating / cooling device. The heating / cooling device surrounds the sample container so as not to contact the sample container.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an electronic weighing balance according to an embodiment of the present invention will be described with reference to FIGS.
[0011]
<Configuration of electronic weighing balance>
As shown in FIG. 1, the electronic weighing balance according to the embodiment of the present invention mainly includes an electronic balance 16, a cylindrical fixing member, a nonmagnetic pressure vessel 11, and a magnetic levitation body.
[0012]
The cylindrical fixing member mainly includes an outer cylinder 33, an upper cylindrical permanent magnet 31, and a flying position control electromagnet 30. The upper cylindrical permanent magnet 31 is disposed at the uppermost inner side of the outer cylinder 33. The flying position control electromagnet 30 is disposed at the innermost lowermost portion of the outer cylinder 33. The cylindrical fixing member is installed on the electronic balance 16.
[0013]
The nonmagnetic pressure vessel 11 is a sealed vessel mainly composed of a thin tube portion and a thick tube portion. The narrow cylinder portion is inserted into the cylindrical fixing member through the hole of the upper cylindrical permanent magnet 31 so as not to contact the outer cylinder 33, the upper cylindrical permanent magnet 31, and the flying position control electromagnet 30. Here, the lower end of the narrow tube portion is closed. The thick tube portion is provided above the thin tube portion, and the lower end is connected to the upper end of the thin tube portion. And the light emission part and the light-receiving part are provided in the side wall of this thick cylinder part so that it may oppose. Note that the upper end of the thick cylindrical portion is closed by the lid 10. That is, the nonmagnetic pressure vessel 11 has a structure in which the upper side can be released. For this reason, in this electronic weighing apparatus, the magnetic levitation body can be pulled out. For this reason, the electronic weighing balance can easily mount the sample and clean the sample container (described later). Therefore, this electronic weighing balance is very easy to use. The nonmagnetic pressure vessel 11 is supported by a frame 15.
[0014]
The magnetic levitation body mainly includes a hollow shaft 22, a sample container 21, a dog 23, an upper permanent magnet 24, and a lower permanent magnet 25. The sample container 21 is a container for storing the sample 20 and is fixed to the upper end of the hollow shaft 22. In the present embodiment, the sample container 21 is surrounded by the heating / cooling device 12. The dog 23 is fixed to the outer peripheral portion of the portion of the hollow shaft 22 below the fixing position of the sample container 21. The upper permanent magnet 24 is fixed inside a portion of the hollow shaft 22 below the position where the dog 23 is fixed. The lower permanent magnet 25 is fixed inside the lowermost part of the hollow shaft 22. The magnetic levitation body is accommodated in the nonmagnetic pressure vessel 11 so that the sample container 21 and the dog 23 are accommodated in the thick cylindrical portion, and the upper permanent magnet 24 and the lower permanent magnet 25 are accommodated in the narrow cylindrical portion. .
[0015]
<Levitating principle of magnetic levitation body>
In FIG. 1, the amount of light detected by the light receiving unit 14 changes when the dog 23 blocks light emitted from the light emitting unit 13. By measuring the relationship between the amount of light detected by the light receiving unit 14 and the position of the magnetic levitation body in the Z-axis (see FIG. 2) direction in advance, the position of the magnetic levitation body in the Z-axis direction can always be detected.
[0016]
FIG. 2 shows the magnitude of thrust acting in the Z-axis direction between the upper cylindrical permanent magnet 31 and the upper permanent magnet 24. Here, the magnetization directions of the upper cylindrical permanent magnet 31 and the upper permanent magnet 24 are opposite to each other.
[0017]
When the upper cylindrical permanent magnet 31 is fixed in FIG. 2, when the Z-axis direction center positions of the upper permanent magnet 24 and the upper cylindrical permanent magnet 31 coincide with each other, the Z-axis upward thrust and the Z-axis downward thrust Is 0, but if the upper permanent magnet 24 is moved downward in the Z-axis, a Z-axis upward thrust is generated in the upper permanent magnet 24. When the upper permanent magnet 24 moves downward in the Z axis, the magnetic force acting between the upper permanent magnet 31 and the upper permanent magnet 31 when the upper permanent magnet 24 is displaced in the radial direction from the center position of the Z axis in a range where the upward thrust in the Z axis monotonously decreases. It is pushed back to the center position of the Z axis by force. That is, it is stable in the radial direction.
[0018]
In FIG. 1, when the magnetic levitation body is placed at a position slightly higher than the position where the weight of the magnetic levitation body and the thrust of the magnetic levitation balance with the Z-axis upward thrust are balanced in the radial direction, a force acts on the magnetic levitation body upward in the Z-axis.
[0019]
The current flowing through the flying position control electromagnet 30 is controlled so as to maintain the position at this time.
[0020]
The weight of the magnetic levitation body and the magnetic attractive force acting between the lower permanent magnet 25 and the levitation position control electromagnet 30 are larger than the Z-axis upward thrust acting between the upper permanent magnet 24 and the upper cylindrical permanent magnet 31. When the magnetic levitation body is further lowered downward, the amount of light detected by the light receiving unit 14 increases, and the current flowing through the levitation position control electromagnet 30 is reduced. As a result, the magnetic levitation body is pulled upward in the Z-axis. Then, the amount of light detected by the light receiving unit 14 is reduced, and the current flowing through the flying position control electromagnet 30 is increased. In this way, the magnetic levitation body is levitated and held at a predetermined position so as not to contact the nonmagnetic pressure vessel 11.
[0021]
When the magnetic levitation body is levitated and held so as not to contact the nonmagnetic pressure vessel 11 in this way, the weight of the magnetic levitation body and the cylindrical fixing member can be measured by the electronic balance 16. That is, the weight of the adsorbed material of the sample 20 can be measured.
[0022]
【The invention's effect】
In the electronic weighing device according to the present invention, the magnetic levitation is controlled by controlling the attractive force acting between the floating position control electromagnet and the lower permanent magnet with respect to the attractive force acting between the cylindrical permanent magnet and the upper permanent magnet. You can balance and float your body. For this reason, in this electronic weighing device, the weight of the fixing member and the magnetic levitation body can be collectively measured. In this electronic weighing device, the sample container is provided on the top of the magnetic levitation body. For this reason, in this electronic weighing device, the influence on the magnetic levitation performance due to convection during heating can be minimized. Moreover, in this electronic weighing apparatus, it is not necessary to use the wire for suspension. For this reason, in this electronic weighing apparatus, it can be set as a structure with low height. Therefore, this electronic weighing device can be made smaller than before. As a result, this electronic weighing device can be manufactured at low cost. Moreover, in this electronic weighing apparatus, if the cylindrical fixing member and the magnetic levitation body are lightened, the weight increase / decrease of the sample can be measured with very high accuracy.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of an electronic weighing apparatus according to the present invention.
FIG. 2 is a longitudinal sectional view showing axial thrust between permanent magnets according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Cover 11 Nonmagnetic pressure vessel 12 Heating / cooling device 13 Light emission part 14 Light reception part 15 Frame 16 Electronic scale 20 Sample 21 Sample container 22 Hollow shaft 23 Dog 24 Upper permanent magnet 25 Lower permanent magnet 30 Levitation position control electromagnet 31 Upper cylinder shape Permanent magnet 33 outer cylinder

Claims (2)

An electronic scale,
An insertion hole extending along the vertical direction, a cylindrical permanent magnet that is magnetized in the axial direction and disposed at the upper portion of the insertion hole so that the axis is along the vertical direction, and a vertical lower side of the cylindrical permanent magnet A floating position control electromagnet, and a fixing member installed on the electronic balance;
A first cylindrical portion that is inserted into the insertion hole through the hole of the cylindrical permanent magnet and closed at the lower end so as not to contact the wall of the insertion hole, the cylindrical permanent magnet, and the electromagnet for floating position control; a closed container having an upper cover portion for closing the second tubular portion lower end disposed above said first tubular portion is coupled to the upper end of the first cylindrical portion, the upper end of the second cylindrical portion,
The rod-shaped member, the sample container fixed to the rod-shaped member, the light shielding portion fixed to the rod-shaped member, and the sample of the rod-shaped member are magnetized in a direction opposite to the magnetization direction of the cylindrical permanent magnet. An upper permanent magnet fixed to a portion below the fixing position of the container, and a lower permanent magnet fixed to a portion of the rod-like member below the fixing position of the upper permanent magnet and attracted to the floating position control electromagnet And the sample container and the light shielding part are accommodated in the second cylinder part, and the upper permanent magnet and the lower permanent magnet are accommodated in the first cylinder part. A levitating body,
A light emitting unit;
A light receiving portion arranged to face the light emitting portion across the light shielding portion;
A current control device for controlling a current flowing through the flying position control electromagnet based on an amount of light received by the light receiving unit;
An electronic weighing device.   The electronic weighing apparatus according to claim 1, further comprising a heating / cooling device surrounding the sample container so as not to contact the sample container.

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