JPS60174941A - Moisture meter for bulk matter and sensor therefor - Google Patents

Abstract

PURPOSE:To measure moisture accurately and quickly by measuring the electrostatic capacitance with a bulk matter compressed to a specified density to correct it by an electric characteristic data by the place of production. CONSTITUTION:A bulk matter 20 is compressed to a specified density, an admittance is built between a pair of electrodes 11 and 12 and the electrostatic capacitance there of is inputted into a transmitter 3 to be converted into current. The output current is inputted into a conversion means 4 to be converted into a data signal of water content. On the other hand, water content in absolute dry of the bulk matter classified by the place of production is measured, inputted with a numeric key 8 and then, a data obtained is stored into a memory means 7 beforeahand. Then, electric characteristic data classified by the place of production of sample bulk matter is selected with a selection means 6, inputted into the conversion means 4 to correct the water content and the results are shown on the display 30. Thus, as the electrostatic capacitance of the bulk matter with the specified density is detected to correct the electric characteristic data classified by the place of production of the sample, water content can be measured quickly at a high accuracy.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a moisture meter that measures the proportion of moisture contained in powdered materials such as sand, and particularly to a moisture meter that can easily, quickly, and accurately obtain measurement results. This is about a moisture meter that can be used.

[Prior art]

The absolute dry method is known as one of the methods for measuring the moisture content of powder and granular materials. The water content of the granular material is measured by removing water from the powder by heating or the like, and subtracting the weight after water removal from the weight before water removal. Although the bone-dry method has the advantage of being able to perform accurate measurements, it has the disadvantage that the measurement operation is complicated and measurement results cannot be obtained immediately.

Another method is to measure the resistance value of powder or granules to obtain the moisture content. This method takes advantage of the fact that the resistance value of granular material changes in proportion to the moisture content. This method is effective for measuring granular materials such as river sand with low electrical conductivity, but the rate of change in resistance value is too small for measuring granular materials such as sea sand with high electrical conductivity. Not practical.

As a method for measuring granular materials such as sea sand, there is a method of measuring the capacitance of the granular material to obtain the moisture content (hereinafter referred to as capacitance measuring method).

However, the relationship between the capacitance and the moisture content of the powder or granular material is a non-linear relationship as shown in FIG. 8(a) under normal conditions.

Furthermore, as shown in A, Kuchi, and C, the curves differ depending on the place and type of sand. Therefore, the conventional measurement of water content by electrostatic capacity measurement has the disadvantage that only inaccurate values can be obtained and it is impractical.

[Purpose of the invention]

The present invention was made for the purpose of eliminating the drawbacks of moisture meters based on the capacitance measurement method and achieving accuracy and speed of measurement results.

[Structure of the invention]

The measures taken to achieve the objectives listed below are as follows. (b) Place the powder to be measured into a container and compress it to a predetermined density. (0) Correct the measured capacitance according to the characteristics of the powder and calculate the moisture content.

[Effect]

These measures work as follows: That is, by compressing the powder to a predetermined density, the relationship between capacitance and water content can be made linear as shown in FIG. 8(b).

Even if such linearity is achieved, the characteristics of the powder or granular material, for example, in the case of sand, the production area and type may vary.

The straight lines are different as shown in Figure 8(b) A, 口, and C. Therefore, by correcting the measured capacitance for each production area, it is possible to determine an accurate moisture content.

〔Example〕

Examples targeting sand will be described below.

FIG. 1 is a perspective view showing an embodiment of the present invention, in which a measurement sensor (2) is connected to a calculation operation unit (9) using a cable (Qf).
), and the arithmetic operation unit (9) has a numeric keypad (8), a display device, and selection buttons for each production area.

First, a sensor (2) for compressing sand to a predetermined density and linearizing the relationship between its capacitance and water content will be described. FIG. 4 is a perspective view of the sensor, and FIG. 6 is a sectional view. In the figure, ``■'' is a lid, which is fixed by a rotating shaft ``-'' so that it can rotate about a point at the end of the main body (B). The lid 153) is rotated (dotted chain line in FIG. 4), and sand, which is the object to be measured, is poured almost completely into the end of the measurement chamber. Then, turn the lid again to close the lid, and turn the handle (■) to compress the sand with the inner lid. The upper lid is slid into the groove (62) of a sturdy lid holder (52') attached to the main body and is firmly held. If the handle wheel is always compressed until it stops rotating during measurement, the density of the sand will be at a predetermined value. Note that the main body @ is a conductor,
Also serves as a measurement electrode. In order to reduce the weight, it is desirable to provide the electrodes separately from the main body and to make the main body (b) of plastic or the like.

The other electrode αη is insulated from the main body (6) by an insulator. A connector (571 is an electrode Ql), a terminal for connecting a cable (lf) for transmitting the admittance between the subspaces to the operation calculation section (9), and a terminal for connecting a cable (lf) for transmitting the admittance between subspaces to the operation calculation unit (9). is provided, and information from the CA thermoelectric couple (c) is also transmitted to the operation calculation section through cable 00. Note that it is also possible to use other temperature sensors instead of the CA thermocouple.

When the measurement is finished and you want to remove the sand from the measurement chamber gap, use the push plate (
If you push the bottom cover in the t direction, the connected bottom cover will move in the L direction, allowing you to easily take out the sand.

Next, the measurement operation will be explained according to FIG.

In the figure, sand (7) compressed to a predetermined density by the sensor (2) constitutes the admittance between the pair of electrodes αη, μs. The capacitance between the electrodes O]), (2) is converted into a current by the transmitter (3). The transmitter (3) has an alternating current oscillation source and has an electrode αυ.

In order to generate a current according to the admittance between electrodes (b) and erase the current due to the resistance between the electrodes (b) and (2), a pulse with the opposite phase to the resistance current is applied.
It outputs only current due to capacitance.

This output current is converted into a water content data signal by the converting means (4) and displayed on the display device (2).

As mentioned above, even if the relationship between capacitance and moisture content is a straight line, the straight line will vary depending on the sand production area.
Therefore, accurate measurements cannot be made unless the conversion ratio from the output current of the transmitter (3) to the moisture content is changed depending on the production area.

This invention realizes this by a storage means (7) and a selection means (6). Storage means (7) includes (71), (72), (78) assigned to each production area.
A memory location is provided for... Each storage location contains data showing the relationship between the output current and moisture content of sand from each production area, i.e. A, B, C of No. 5111(b).
, D are stored. The selection means (6) uses the selection button () to determine the selected output current as X. When using a microcomputer, a set can be applied directly in the program. Therefore, A according to the production area in advance.

If the data of B, C, and D are stored in the storage means (7), the moisture content can be accurately measured by pressing the selection button θO of the corresponding production area.

In this example, temperature compensation is performed to further improve measurement accuracy. That is, as shown in FIG. 2, a CA thermocouple α field is provided inside the sensor (2), and the moisture content is corrected based on its output current. If the temperature measured by CA thermocouple a3 is t, the corrected moisture content Y is Y=Ya ・ (iu+v)
+++ It can be expressed as (2). Particularly when using a microcomputer, it is also possible to measure the correction values in advance and store them as a table without using one set.

Next, the operation of storing data A, B, C, and D in advance in the storage means (7) will be explained. Prepare two types of sand of the same origin and type, but with different moisture contents. Accurately determine the moisture content of each sand using the bone dry method. Enter the moisture content of the sand with the lower moisture content using the numeric keypad (
Enter from 8).

At this time, press the numeric keypad (8) to the storage location of the storage device (7) selected by the selection button (5).
The signal from is stored as data A. Next, this sand is put into the sensor (1) and used as a designated secret residence. At this time, the output current of the transmitter (3) is stored as data B in the storage means (7). If you repeat the same operation for sand with a high moisture content, data C and D will be stored as a storage means (7)
is memorized. From now on, when measuring the moisture content of sand from the same production area, press the corresponding selection button ■.
Accurate measurements can be made based on the data A, B, and CD.

Next, an example using a microcomputer will be described. Its circuit configuration is as shown in Figure 6,
The same or equivalent parts as in FIGS. 1 to 5 are given the same reference numerals. The input port @υ is composed of a multiplexer and the like. This receives the selection signal given from the CPU 641 via the signal line - and outputs the signal from the selection button) to the CPU N, or outputs the signal from the A/IJ converter (80) to the CPU. Select whether to output the signal from the numeric keypad (8) to the CPU (841).The role of the selection button (a) can also be played by the numeric keypad (8)I. No is CPU-, RAM all,
It is composed of ROM 11161. ROM @
A program for controlling the CPU 4941 is written in 51.

The programs written in the ROM- are shown in flowcharts as shown in FIGS. 7 and 8.

The seventh column is a flowchart of a storage process for previously storing data of A, B, C, and D used for converting measured voltage X into moisture content Y by region of production. The flow of the process is almost the same as in the previous embodiment. For example, the moisture content in Step (C) and Step (Company) needs to be accurate and measured by an absolute dry method or the like. In this example, sand (a)
, (b) are inserted into the sensor to obtain the measured voltage V.
If known, the measured voltage V can be input from the numeric keypad. The conversion formula in step (2) is the same as the above-mentioned formula [1].

By using a microcomputer, it is easy to change even if the basic type of the conversion formula changes.
Even in the case of the following equation, it can be handled simply by changing the conversion equation in step (2).

By the way, the admittance of sea sand changes depending on the amount of salt it contains. This device can also be used as a sea sand salinity determiner by displaying a signal indicating that the magnitude of the current in accordance with the admittance generated in the transmitter (3) exceeds a predetermined value.

〔Effect of the invention〕

As described above, according to the present invention, the moisture content of powder or granular material can be measured accurately and quickly. Furthermore, the measurement equipment is simplified,
A moisture meter that can be miniaturized and easily carried can be realized.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing an embodiment of the present invention, FIG. 2 is a block diagram for explaining the operation, and FIG.
), Figure 8(b) is a graph showing the relationship between measurement voltage and moisture content, Figure 4 is a perspective view of the sensor, Figure 5 is a cross-sectional view of the sensor, and Figure 6 is a graph showing the relationship between measurement voltage and moisture content. FIG. 7 is a flowchart of the storage process, and FIG. 8 is a flowchart of the measurement process. (2)...sensor, (8) , , numeric keypad, (9
)... Arithmetic operation unit, aQ... Cable, Oη, o4
...electrode, (to)...CA@electrode, (to)...display device, (to)...selection button, (foundation)...microcomputer. 7Xφ Relaxation Figure 4 Figure 5 Body n 7th WJ No. 811

Claims (1)

[Scope of Claims] (1) A sensor for measuring electrical characteristics of powder or granular material, comprising: 1 a transmitter that converts the electrical characteristics into an electrical signal; and a transmitter that corresponds to the type of the powder or granular material. a storage means for storing in advance the relationship between the change in the moisture content of the powder and the change in the electric signal, that is, a conversion factor signal; and a selection means for selecting and outputting the conversion factor signal. , □ conversion means for converting the electrical signal into a display signal representing the moisture content based on the conversion factor signal selected by the selection means; 1 display means for displaying the display signal; A moisture meter for powder and granular materials, which is characterized by being equipped with. (2) The transmitter includes: means for converting the admittance of the powder into a current; and means for dividing the current into a resistance component and a capacitance component and outputting only the current related to the capacitance component. A moisture meter for powder or granular material according to claim 1, characterized in that: (3) The conversion means is characterized by being equipped with a means for correcting the moisture content based on the output of the temperature sensor. (4) The display means is characterized by being equipped with an LED. 5) The display means includes: means for determining that the admittance current of the transmitter exceeds a predetermined value and outputting a discrimination signal; and means for displaying the presence or absence of the discrimination signal. A cylindrical container according to any one of claims 2 to 4, characterized in that: a lid rotatably provided around a point on an upper end of the container; The inner lid is attached to the lid by a movable means having an outer diameter slightly smaller than the inner diameter and changing the distance between the inner surface and the inner surface of the lid, and the inner lid is attached to both ends of the outer member of the lid to operate the movable means. A sensor for a powder moisture meter, comprising: a push plate having an outer diameter slightly smaller than the inner diameter of the container; and an electrode having connection means to the outside. (7) The sensor according to claim 6, wherein the movable means includes a bolt and a nut.