JP2003302324A - Moisture meter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a temperature of a sample placed on a weighing bowl from an apart place in a heat drying type moisture meter. <P>SOLUTION: The moisture meter is provided with a temperature sensor 3 proximity to a heat source 2 such as a straight halogen lamp. A reflector 4 is arranged proximity to the temperature sensor 3 in a way that a part of heat beams from the heat source is reflected by the reflector 4 toward the temperature sensor. The temperature sensor 3 actually measures the temperature of the weighing bowl 12 from the place apart from the weighing bowl 12 by adjusting an amount of the reflection by adjusting an angle of the reflector 3. This eliminates the necessity of arranging the temperature sensor proximity to the weighing bowl 12 causing inconvenience for loading/unloading the weighing bowl 12 with the sample, and also prevents the heat source 2 and the temperature sensor 3 from adhering vaporized components of vapor and oiliness from the sample by a translucent separator 5 separating the temperature sensor 3 and the heat source 2. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture meter, and more particularly to a moisture meter constructed so as to properly control the temperature of heating means in a heat-drying moisture meter.

[0002]

2. Description of the Related Art As one of the methods for measuring the water content of a sample, a method of measuring the electrical resistance of the sample, or measuring the attenuation due to reflection or transmission of infrared rays is used. Since the method of measurement is limited in the type of sample to be measured, and the method of measuring the amount of attenuation due to reflection or transmission of infrared rays is very expensive, either method can be used to determine the moisture content of various materials. It can be said that the measurement method is not very versatile.

On the other hand, a heat-drying type moisture meter is a device for measuring the water content of a sample by heating the sample to evaporate the water content and changing (decreasing) the mass of the sample before and after heating and drying. Can be provided at a relatively low cost, and can handle a wide variety of samples in a relatively short time.
Widely used as a moisture meter. Unless otherwise specified, the term “moisture meter” refers to this heat-drying type moisture meter.

[0004]

FIG. 3 shows an example of the configuration of a conventional moisture meter. The moisture meter is roughly composed of a heating unit 10 having a means for heating a sample and a mass measuring unit 11 for measuring the mass of the sample. The heating unit 10 is provided with heating means 13 for heating the sample placed on the weighing pan 12 of the mass measuring unit 11. As a heating means, for example, a halogen lamp, an infrared lamp, a sheath heater, etc. are used, but recently, a halogen lamp tends to be used in many cases from the viewpoint of shortening the temperature rising / measuring time.

Here, when measuring the water content of a sample with a moisture meter, a target value of heating temperature is set in accordance with the type and capacity of the sample, and basically, while measuring the temperature of this sample, Heating means 1 so that the temperature reaches the target value
3 will be controlled. However, in this case, if the temperature of the sample itself or the temperature of the weighing dish 12 is directly measured, the mass of the temperature sensor interferes with the mass measuring unit 11, and accurate mass measurement becomes impossible.

Therefore, the temperature is detected without contact. That is, the temperature of the weighing dish 12 (hereinafter referred to as "plate temperature") is detected by the sensor as the temperature which is the closest to the target temperature. Therefore, the temperature sensor is arranged as close to the weighing pan 12 as possible. The apparatus of FIG. 3 is configured from this point of view, and the temperature sensor 14 is arranged directly above the weighing dish 12 and as close to the weighing dish 12 as possible.

However, if the temperature sensor 14 is arranged at this position, water vaporized from the sample, vaporized oil, etc. will contact and adhere to the temperature sensor 14, and the performance of the temperature sensor 14 will deteriorate over time. For this reason, for example, there has been proposed one in which the temperature sensor 14 is housed in a metal cylinder so that the temperature sensor 14 does not adhere to them. However, the provision of the metal cylinder increases the heat capacity of the temperature sensor 14 portion, which also makes it impossible to accurately detect the temperature. In addition, this arrangement of the temperature sensor creates a shadow of the temperature sensor 14 on a part of the weighing dish 12, which is not preferable in terms of uniform heating of the sample.

Further, by disposing the temperature sensor 14 close to the weighing dish 12, the temperature sensor 14 interferes with the work of loading and unloading the sample to and from the weighing dish 12, which lowers the work efficiency and spills the sample. It causes inconvenience such as being lost. Therefore, it is conceivable that the temperature sensor 14 can be moved to another position during the sample loading / unloading work, but it is inevitable that the device becomes complicated.

The configuration of FIG. 4 is configured in view of the problems of the configuration of FIG. As shown in the figure, the temperature sensor 14 is arranged at a position apart from the weighing pan 12. As a result, it is possible to improve the workability when the oil or the like is attached to the temperature sensor 14 or when the sample is loaded / unloaded with the above-mentioned configuration, but the amount of light from the heating means 13, that is, the amount of the heat beam is significantly reduced. Resulting in. Therefore, the temperature detected by the temperature sensor 14 decreases as the temperature of the weighing dish 12 rises, and the temperature change rate detected by the temperature sensor 14 becomes lower than the temperature change rate of the weighing dish 12. In such a situation, the heating means 1
There is a possibility that the control of No. 3 becomes extremely difficult, or the control itself becomes impossible.

In view of such a situation, a method of correcting the temperature detected by the temperature sensor 14 to the temperature on the dish of the weighing dish 12 by using a specific coefficient may be considered, but the amount of the sample, the amount of water vapor generated, etc. However, there are many arithmetic elements that cannot be specified numerically, and it is difficult to set an appropriate coefficient, and this method is not practical.

[0011]

SUMMARY OF THE INVENTION The present invention is constructed in view of the above-mentioned problems, in which a temperature sensor is arranged at a position distant from a weighing pan, and a reflecting plate is arranged close to the temperature sensor. To be done. Set the position of the temperature sensor and the size of the reflection plate, or the mounting angle of the reflection plate to a predetermined value so that the temperature detected by the temperature sensor at a position away from the weighing pan becomes equal to the temperature on the pan of the weighing plate. A moisture meter characterized in that the temperature on the plate is indirectly and accurately detected by this temperature sensor.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The temperature sensor is arranged at a position away from the weighing pan where it does not interfere with the sample loading and unloading work, etc. A reflector is placed close to this temperature sensor. The size of the reflection plate, the setting of the mounting angle, etc. are determined, for example, by examining the shape, heat capacity, and arrangement of each member when a moisture meter is prototyped.

That is, from the distance from the heat source, the arrangement position, the amount of heat beam (light), the amount of reflection of the heat beam to the temperature sensor, etc., the set value at which the temperature detected by the temperature sensor and the temperature on the pan of the weighing dish match It is almost possible to calculate, but more practically, it is desirable to actually measure and adjust the temperature during trial manufacture of the device.

Specifically, a sensor for directly measuring the temperature of the weighing pan is arranged. That is, since the mass measurement of the sample is not performed at the time of this prototype, the test temperature sensor is directly attached to the weighing pan without considering the influence on the mass measurement unit.
The temperature of the weighing pan is measured directly with this test temperature sensor.

On the other hand, the position of the temperature sensor, the size of the reflecting plate, the mounting angle of the reflecting plate, etc. are adjusted so that the measured temperature of the temperature sensor installed in this apparatus matches the measured temperature of the test temperature sensor. In this way, the temperature measured by the temperature sensor is adjusted to match the temperature measured by the test temperature sensor. If the temperature measured by the temperature sensor is adjusted to match, the values of the position of the temperature sensor in this state, the size of the reflector, the position of the reflector, the mounting angle of the reflector, etc. are specified. Mass production of the moisture meter. As a result, all the moisture meters as mass-produced products can detect the temperature of the weighing pan very accurately at a position apart from the weighing pan, and the proper temperature control of the heat source can be performed. If the above-mentioned value is set so that the temperature change detected by the temperature sensor changes slightly earlier than the temperature change of the weighing pan, the heat source is controlled prior to the temperature change of the sample. It will be easier.

[0016]

Embodiments of the present invention will be described below with reference to FIGS. A heat source arrangement space 1 is formed in the heating unit 10, and a straight tube type halogen lamp 2 is arranged in the heat source arrangement space 1 as a heat source. A temperature sensor 3 is arranged apart from the weighing dish 12 of the weight measuring unit 11 and closer to the heat source 2 than the weighing dish 12.

Reference numeral 4 denotes a reflector arranged in the vicinity of the temperature sensor 3 and is configured to reflect a part of the heat beam (light) emitted from the heat source 2 to the temperature sensor 3 side. Reference numeral 5 denotes a transparent plate formed of a transparent material such as glass, which prevents water vapor rising from the sample, vaporized oil, and the like from adhering to the heat source 2 and the temperature sensor 3.

In FIG. 2, the position where the temperature sensor 3 is arranged, the width W of the reflection plate 4, the mounting angle α of the reflection plate 4, and the like are as described above, the detected temperature of the temperature sensor 3 and the temperature of this detected temperature. The values are set so that the rate of change is substantially equal to the actual temperature of the weighing pan 12 and is equal to or slightly faster than the rate of temperature change of the weighing pan 12.

In the above structure, when measuring the water content of the sample, the temperature for heating the sample is set according to the amount of the sample, the type of the sample, etc., and the heating means is controlled to reach this set temperature. . Heat beam B from heating means 2
Is irradiated on the sample on the weighing dish 12 to heat the sample. At this time, a part of the beam 1B is also radiated to the temperature sensor 3 side via the reflection plate 4, and as described above, the temperature detected by the temperature sensor 3 and the change in the temperature detected are not measured by the weighing plate 12.
Is used for the temperature control of the heat source 2 as the temperature and the temperature change thereof, and the heating temperature of the sample is controlled to a set value.

The constituent material of the reflecting plate 3 can be selected according to the purpose, such as a metallic material having high heat conductivity in consideration of heat dissipation, or a reflecting surface which is a mirror surface to enhance reflectance. is there.

In the present invention, sealing the heat source arrangement space 1 with the transparent plate 5 is not an essential requirement of the present invention.
Since it becomes possible to arrange the temperature sensor 3 near the heat source 2, if the transparent plate 5 is used to seal the heat source arrangement space 1, the temperature sensor 3 and the heat source 2 are separated from the water vapor rising from the sample or the vaporized oil content. It becomes possible to protect.

By arranging the transparent plate 5, the transparent plate 5 serves as a secondary radiator, and it becomes possible to uniformly heat the plate. That is, even if the heat source such as a straight tube type halogen lamp having a comparatively limited light source is arranged, the transparent plate 5 is arranged so that uniform heating can be performed, and a round and large size is provided to make the plate temperature uniform. It is not necessary to use a halogen lamp (heat source 13 in FIGS. 3 and 4).

[0023]

As described above, according to the present invention, the temperature of the weighing pan is set by setting the position of the temperature sensor, the position of the reflecting plate, the mounting angle of the reflecting plate, the size, etc. to predetermined values. It is possible to control the heat source with an accuracy close to that in the case of measuring directly, and it is possible to improve the accuracy of moisture measurement of the sample.

Further, since the temperature sensor itself is arranged at a position apart from the weighing pan, it becomes possible to remarkably reduce the adhesion of water vapor, vaporized oil content and other contained components from the sample, especially the heating means and If this temperature sensor is shielded from the sample side by a transparent plate such as a glass plate, the adhesion of these can be almost completely prevented, and high performance as a moisture meter can be maintained for a long period of time. The use of this transparent plate is particularly effective when a halogen lamp is used as a heat source, since the halogen lamp is susceptible to surface dirt and causes characteristic changes.

Further, since there is no temperature sensor in the vicinity of the weighing pan, work such as loading and unloading of the sample can be carried out smoothly.

[Brief description of drawings]

FIG. 1 is a sectional view mainly showing a heating part of a moisture meter showing an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing an irradiation state of a heat beam from the heat source of FIG.

FIG. 3 is a cross-sectional view mainly showing a heating part of a moisture meter showing a conventional configuration example.

FIG. 4 is a cross-sectional view mainly showing a heating portion of a moisture meter showing another conventional configuration example.

[Explanation of symbols]

1 heat source arrangement space 2 heat source 3 Temperature sensor 4 reflector 5 transparent plate 10 heating unit 11 Mass measurement section 12 weighing dish B heat beam

Continued front page    (72) Inventor Akira Ota             1-243 Asahi, Kitamoto City, Saitama Stock Market             A & D Development and Technology Center             Within (72) Inventor Masahiro Kanno             1-243 Asahi, Kitamoto City, Saitama Stock Market             A & D Development and Technology Center             Within

Claims (4)

[Claims] 1. A sample placed on a weighing pan of a weight measuring unit is heated and dried by the heat source by controlling the heat source according to the temperature detected by the temperature sensor, and the mass of the sample before heating and the heat drying are performed. In the device that measures the water content of the sample from the mass of the sample later, the temperature sensor is placed at a position away from the weighing pan, and a part of the heat beam emitted from the heat source with respect to the temperature sensor is the temperature concerned. A reflection plate is arranged close to the temperature sensor so as to be reflected by the sensor, and the moisture sensor is configured so that the temperature detected by the temperature sensor is substantially equal to the temperature of the weighing dish at a position distant from the weighing dish. . 2. The moisture meter according to claim 1, wherein the temperature sensor is arranged in an upper space of the weighing dish and in a heat source arrangement space in which the heat source is located. 3. The moisture meter according to claim 2, wherein the heat source arrangement space is separated from the weighing dish arrangement space by a transparent plate. 4. The moisture meter according to claim 1, wherein the heat source is a straight tube type halogen lamp.